I am trying to create my own custom show case view , In which i have left button , right button and a tab bar view.
I want to highlight the buttons with round circle around it.
I am able to create a single Circle around my button by subclass UIView
But what i do so user swipe from left to right it will change the Circle to right button and the left button hide.
Here is my subclass of UIView
//--------.h class
#import <UIKit/UIKit.h>
#interface IntroView : UIView
- (void)drawRect:(CGRect)rect withBtnRect:(CGRect)btnrect ;
#end
//------. m class
#import "IntroView.h"
#implementation IntroView
- (id)initWithFrame:(CGRect)frame
{
self = [super initWithFrame:frame];
if (self) {
// Initialization code
}
self.backgroundColor= [[UIColor blackColor] colorWithAlphaComponent:0.3];
return self;
}
- (void)drawRect:(CGRect)rect {
CGRect maskRect= CGRectMake(5, 5, 100, 100);//set and pass this maskRect
CGRect rBounds = self.bounds;
CGContextRef context = UIGraphicsGetCurrentContext();
// Fill background with 40% gray
CGContextSetFillColorWithColor(context, [[[UIColor grayColor] colorWithAlphaComponent:0.4] CGColor]);
CGContextFillRect(context, rBounds);
// Draw the window 'frame'
CGContextSetStrokeColorWithColor(context, [[UIColor whiteColor] CGColor]);
CGContextSetLineWidth(context,2);
CGContextStrokeEllipseInRect(context, maskRect);
// make the window transparent
CGContextSetBlendMode(context, kCGBlendModeClear);
CGContextFillEllipseInRect (context, maskRect);
}
/*
// Only override drawRect: if you perform custom drawing.
// An empty implementation adversely affects performance during animation.
- (void)drawRect:(CGRect)rect
{
// Drawing code
}
*/
#end
And inside my tabbar first view i call using
#import "IntroView.h"
then
- (void)viewDidLoad
{
IntroView *vw_intro=[[IntroView alloc]initWithFrame:CGRectMake(0, 0, 320, 480)];
vw_intro.tag=1000;
[self.view addSubview:vw_intro];
[super viewDidLoad];
// Do any additional setup after loading the view, typically from a nib.
}
Here is my output
And expected Output on Slide right to left , and so or in reverse (like we do in showcase android library )
In IntroView.h
#import <UIKit/UIKit.h>
#interface IntroView : UIView
- (id)initWithFrame:(CGRect)frame introElements:(NSArray *)iElements;
- (void)showIntro;
#end
In IntroView.m
#import "IntroView.h"
#implementation IntroView
{
CAShapeLayer *mask;
NSArray *introElements;
NSUInteger currentIndex;
}
- (id)initWithFrame:(CGRect)frame introElements:(NSArray *)iElements
{
self = [super initWithFrame:frame];
if (self) {
// Initialization code
introElements = iElements;
mask = [CAShapeLayer layer];
[mask setFillColor:[[UIColor grayColor] colorWithAlphaComponent:0.8f].CGColor];
[mask setFillRule:kCAFillRuleEvenOdd];
[self.layer addSublayer:mask];
UISwipeGestureRecognizer *swipeGestureRecognizer = [[UISwipeGestureRecognizer alloc] initWithTarget:self action:#selector(userDidSwipe)];
swipeGestureRecognizer.direction = UISwipeGestureRecognizerDirectionRight;
[self addGestureRecognizer:swipeGestureRecognizer];
}
return self;
}
- (void)userDidSwipe
{
[self showIntroAtIndex:currentIndex+1];
}
- (void)showIntro
{
//Initial index by default
[self showIntroAtIndex:0];
}
- (void)showIntroAtIndex:(NSUInteger)index
{
currentIndex = index;
CGRect rect = [[introElements objectAtIndex:index] CGRectValue];
UIBezierPath *maskPath = [UIBezierPath bezierPathWithRect:self.bounds];
UIBezierPath *elementPath = [UIBezierPath bezierPathWithRoundedRect:rect cornerRadius:3.0f];
[maskPath appendPath:elementPath];
// Animate
CABasicAnimation *animation = [CABasicAnimation animationWithKeyPath:#"path"];
animation.timingFunction = [CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionEaseOut];
animation.duration = 0.3f;
animation.fromValue = (__bridge id)(mask.path);
animation.toValue = (__bridge id)(maskPath.CGPath);
[mask addAnimation:animation forKey:#"path"];
mask.path = maskPath.CGPath;
}
In ViewController
- (void)viewDidLoad {
[super viewDidLoad];
// Do any additional setup after loading the view, typically from a nib.
NSArray *viewElements = [NSArray arrayWithObjects:[NSValue valueWithCGRect:button1.frame],[NSValue valueWithCGRect:button2.frame], nil];
IntroView *introView = [[IntroView alloc]initWithFrame:self.view.bounds introElements:viewElements];
[self.view addSubview:introView];
[introView showIntro];
}
Note: i made a highlight to the UIControl frame, if you need a circle highlight, update the changes in the CGRect.
I'm stumped by what I thought would be a simple problem.
I'd like to draw views connected by lines, animate the position of the views and have the connecting line animate too. I create the views, and create a line between them like this:
- (UIBezierPath *)pathFrom:(CGPoint)pointA to:(CGPoint)pointB {
CGFloat halfY = pointA.y + 0.5*(pointB.y - pointA.y);
UIBezierPath *linePath=[UIBezierPath bezierPath];
[linePath moveToPoint: pointA];
[linePath addLineToPoint:CGPointMake(pointA.x, halfY)];
[linePath addLineToPoint:CGPointMake(pointB.x, halfY)];
[linePath addLineToPoint:pointB];
return linePath;
}
-(void)makeTheLine {
CGPoint pointA = self.viewA.center;
CGPoint pointB = self.viewB.center;
CAShapeLayer *lineShape = [CAShapeLayer layer];
UIBezierPath *linePath=[self pathFrom:pointA to:pointB];
lineShape.path=linePath.CGPath;
lineShape.fillColor = nil;
lineShape.opacity = 1.0;
lineShape.strokeColor = [UIColor blackColor].CGColor;
[self.view.layer addSublayer:lineShape];
self.lineShape = lineShape;
}
It draws just how I want it to. My understanding from the docs is that I am allowed to animate a shape's path by altering it in an animation block, like this:
- (void)moveViewATo:(CGPoint)dest {
UIBezierPath *destPath=[self pathFrom:dest to:self.viewB.center];
[UIView animateWithDuration:1 animations:^{
self.viewA.center = dest;
self.lineShape.path = destPath.CGPath;
}];
}
But no dice. The view position animates as expected, but the line connecting to the other view "jumps" right away to the target path.
This answer implies that what I'm doing should work. And this answer suggests a CABasic animation, which seems worse to me since (a) I'd then need to coordinate with the much cooler block animation done to the view, and (b) when I tried it this way, the line didn't change at all....
// worse way
- (void)moveViewATo:(CGPoint)dest {
UIBezierPath *linePath=[self pathFrom:dest to:self.viewB.center];
[UIView animateWithDuration:1 animations:^{
self.viewA.center = dest;
//self.lineShape.path = linePath.CGPath;
}];
CABasicAnimation *morph = [CABasicAnimation animationWithKeyPath:#"path"];
morph.duration = 1;
morph.toValue = (id)linePath.CGPath;
[self.view.layer addAnimation:morph forKey:nil];
}
Thanks in advance.
Thanks all for the help. What I discovered subsequent to asking this is that I was animating the wrong property. It turns out, you can replace the layer's shape in an animation, like this:
CABasicAnimation *morph = [CABasicAnimation animationWithKeyPath:#"path"];
morph.duration = 1;
morph.fromValue = (__bridge id)oldPath.path;
morph.toValue = (__bridge id)newPath.CGPath;
[line addAnimation:morph forKey:#"change line path"];
line.path=linePath.CGPath;
I guess this is all you need:
#import "ViewController.h"
#interface ViewController ()
//the view to animate, nothing but a simple empty UIView here.
#property (nonatomic, strong) IBOutlet UIView *targetView;
#property (nonatomic, strong) CAShapeLayer *shapeLayer;
#property NSTimeInterval animationDuration;
#end
#implementation ViewController
- (void)viewDidLoad {
[super viewDidLoad];
//the shape layer appearance
self.shapeLayer = [[CAShapeLayer alloc]init];
self.shapeLayer.strokeColor = [UIColor blackColor].CGColor;
self.shapeLayer.fillColor = [UIColor clearColor].CGColor;
self.shapeLayer.opacity = 1.0;
self.shapeLayer.lineWidth = 2.0;
[self.view.layer insertSublayer:self.shapeLayer below:self.targetView.layer];
//animation config
self.animationDuration = 2;
}
- (UIBezierPath *)pathFrom:(CGPoint)pointA to:(CGPoint)pointB {
CGFloat halfY = pointA.y + 0.5*(pointB.y - pointA.y);
UIBezierPath *linePath=[UIBezierPath bezierPath];
[linePath moveToPoint: pointA];
[linePath addLineToPoint:CGPointMake(pointA.x, halfY)];
[linePath addLineToPoint:CGPointMake(pointB.x, halfY)];
[linePath addLineToPoint:pointB];
return linePath;
}
- (void) moveViewTo: (CGPoint) point {
UIBezierPath *linePath= [self pathFrom:self.targetView.center to:point];
self.shapeLayer.path = linePath.CGPath;
//Use CAKeyframeAnimation to animate the view along the path
//animate the position of targetView.layer instead of the center of targetView
CAKeyframeAnimation *viewMovingAnimation = [CAKeyframeAnimation animationWithKeyPath:#"position"];
viewMovingAnimation.duration = self.animationDuration;
viewMovingAnimation.path = linePath.CGPath;
//set the calculationMode to kCAAnimationPaced to make the movement in a constant speed
viewMovingAnimation.calculationMode =kCAAnimationPaced;
[self.targetView.layer addAnimation:viewMovingAnimation forKey:viewMovingAnimation.keyPath];
//draw the path, animate the keyPath "strokeEnd"
CABasicAnimation *lineDrawingAnimation = [CABasicAnimation animationWithKeyPath:#"strokeEnd"];
lineDrawingAnimation.duration = self.animationDuration;
lineDrawingAnimation.fromValue = [NSNumber numberWithDouble: 0];
lineDrawingAnimation.toValue = [NSNumber numberWithDouble: 1];
[self.shapeLayer addAnimation:lineDrawingAnimation forKey:lineDrawingAnimation.keyPath];
//This part is crucial, update the values, otherwise it will back to its original state
self.shapeLayer.strokeEnd = 1.0;
self.targetView.center = point;
}
//the IBAction for a UITapGestureRecognizer
- (IBAction) viewDidTapped:(id)sender {
//move the view to the tapped location
[self moveViewTo:[sender locationInView: self.view]];
}
#end
Some explanation:
For UIViewAnimation, the property value is changed when the
animation is completed. For CALayerAnimation, the property value is
never change, it is just an animation and when the animation is
completed, the layer will go to its original state (in this case, the
path).
Putting self.lineShape.path = linePath.CGPath doesn't work is
because self.linePath is a CALayer instead of a UIView, you
have to use CALayerAnimation to animate a CALayer
To draw a path, it's better to animate the path drawing with keyPath
strokeEnd instead of path. I'm not sure why path worked in the
original post, but it seems weird to me.
CAKeyframeAnimation (instead of CABasicAnimation or UIViewAnimation) is used to animate the view along the path. (I guess you would prefer this to the linear animation directly from start point to end point). Setting calculationMode to kCAAnimationPaced will give a constant speed to the animation, otherwise the view moving will not sync with the line drawing.
I have a CAShapeLayer in which an arc is added using UIBezierPath. I saw a couple of posts (one actually) here on stackoverflow but none seemed to give me the answer. As said in the title I would like to animate an arc (yes it will be for a pie chart).
How can one accomplish an animation from an "empty" arc to the fully extended one? Kinda like a curved progress bar. Is it really impossible to do it via CoreAnimation?
Here's how I "do" the arc. Oh and ignore the comments and calculation since I'm used to counter clockwise unit circle and apple goes clockwise. The arcs appear just fine, I only need animation:
//Apple's unit circle goes in clockwise rotation while im used to counter clockwise that's why my angles are mirrored along x-axis
workAngle = 6.283185307 - DEGREES_TO_RADIANS(360 * item.value / total);
//My unit circle, that's why negative currentAngle
[path moveToPoint:CGPointMake(center.x + cosf(outerPaddingAngle - currentAngle) * (bounds.size.width / 2), center.y - (sinf(outerPaddingAngle - currentAngle) * (bounds.size.height / 2)))];
//Apple's unit circle, clockwise rotation, we add the angles
[path addArcWithCenter:center radius:120 startAngle:currentAngle endAngle:currentAngle + workAngle clockwise:NO];
//My unit circle, counter clockwise rotation, we subtract the angles
[path addLineToPoint:CGPointMake(center.x + cosf(-currentAngle - workAngle) * ((bounds.size.width / 2) - pieWidth), center.y - sinf(-currentAngle - workAngle) * ((bounds.size.height / 2) - pieWidth))];
//Apple's unit circle, clockwise rotation, addition of angles
[path addArcWithCenter:center radius:120 - pieWidth startAngle:currentAngle + workAngle endAngle:currentAngle - innerPaddingAngle clockwise:YES];
//No need for my custom calculations since I can simply close the path
[path closePath];
shape = [CAShapeLayer layer];
shape.frame = self.bounds;
shape.path = path.CGPath;
shape.fillColor = kRGBAColor(255, 255, 255, 0.2f + 0.1f * (i + 1)).CGColor; //kRGBAColor is a #defined
[self.layer addSublayer:shape];
//THIS IS THE PART IM INTERESTED IN
if (_shouldAnimate)
{
CABasicAnimation *pieAnimation = [CABasicAnimation animationWithKeyPath:#"path"];
pieAnimation.duration = 1.0;
pieAnimation.removedOnCompletion = NO;
pieAnimation.fillMode = kCAFillModeForwards;
//from and to are just dummies so I dont get errors
pieAnimation.fromValue = [NSNumber numberWithInt:0]; //from what
pieAnimation.toValue = [NSNumber numberWithFloat:1.0f]; //to what
[shape addAnimation:pieAnimation forKey:#"animatePath"];
}
Here is an implementation of a CALayer based on CAShapeLayer:
ProgressLayer.h/m
#import <QuartzCore/QuartzCore.h>
#interface ProgressLayer : CAShapeLayer
-(void) computePath:(CGRect)r;
-(void) showProgress;
#end
#import "ProgressLayer.h"
#implementation ProgressLayer
-(id)init {
self=[super init];
if (self) {
self.path = CGPathCreateWithEllipseInRect(CGRectMake(0, 0, 50, 50), 0);
self.strokeColor = [UIColor greenColor].CGColor;
self.lineWidth=40;
self.lineCap = kCALineCapRound;
self.strokeEnd=0.001;
}
return self;
}
-(void) computePath:(CGRect)r {
self.path = CGPathCreateWithEllipseInRect(r, 0);
}
-(void)showProgress {
float advance=0.1;
if (self.strokeEnd>1) self.strokeEnd=0;
CABasicAnimation * swipe = [CABasicAnimation animationWithKeyPath:#"strokeEnd"];
swipe.duration=0.25;
swipe.fromValue=[NSNumber numberWithDouble:self.strokeEnd];
swipe.toValue= [NSNumber numberWithDouble:self.strokeEnd + advance];
swipe.fillMode = kCAFillModeForwards;
swipe.timingFunction= [CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionEaseInEaseOut];
swipe.removedOnCompletion=NO;
self.strokeEnd = self.strokeEnd + advance;
[self addAnimation:swipe forKey:#"strokeEnd animation"];
}
#end
I used this layer as a backing layer of an UIView:
#import "ProgressView.h"
#import "ProgressLayer.h"
#implementation ProgressView
-(id)initWithCoder:(NSCoder *)aDecoder {
self=[super initWithCoder:aDecoder];
if (self) {
[(ProgressLayer *)self.layer computePath:self.bounds];
}
return self;
}
-(void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event {
ProgressLayer * l = self.layer;
[l showProgress];
}
- (void)drawRect:(CGRect)rect {
[[UIColor redColor] setStroke];
UIRectFrame(self.bounds);
}
+(Class)layerClass {
return [ProgressLayer class];
}
#end
Before you create your animation you want to set your shape's strokeEnd to 0.
Then, use the key #"strokeEnd" instead of #"path"... Keys for CAAnimations are generally the name of the property you want to animate.
Then you can do the following:
[CATransaction begin]
CABasicAnimation *animation = [CABasicAnimation animationWithKeyPath:#"strokeEnd"];
animation.duration = 1.0f;
animation.removedOnCompletion = NO;
animation.fromValue = #0; //shorthand for creating an NSNumber
animation.toValue = #1; //shorthand for creating an NSNumber
[self addAnimation:animation forKey:#"animateStrokeEnd"];
[CATransaction commit];
You have to use the proper keys. "path" and "animatePath" don't mean anything to it - you have to use "strokeEnd" for your key/keypath. If you need to fiddle with your fill color, you use fillColor. The full list is here:
https://developer.apple.com/library/ios/documentation/GraphicsImaging/Reference/CAShapeLayer_class/Reference/Reference.html
I have been reading the documentation on CAShapeLayer but I still don't quite get it.
From my understanding, Layer is always flat and its size is always a rectangle.
CAShapeLayer on the other hand, allows you to define a layer that is not just rectangle-like. It can be a circle shape, triangle etc as long as you use it with UIBezierPaths.
Is my understanding off here?
What I had in mind is, for example, a tennis ball that bounces off the edges on the screen (easy enough), but I would like to show a little animation not using image animations - I would like it to show a little "squeezed" like animation as it hits the edge of the screen and then bounces off. I am not using a tennis ball image. Just a yellow color filled circle.
Am I correct here with CAShapeLayer to accomplish this? If so, can you please provide a litle example? Thanks.
While you do use a path to define the shape of the layer, it is still created with a rectangle used to define the frame/bounds. Here is an example to get you started:
TennisBall.h:
#import <UIKit/UIKit.h>
#interface TennisBall : UIView
- (void)bounce;
#end
TennisBall.m:
#import <QuartzCore/QuartzCore.h>
#import "TennisBall.h"
#implementation TennisBall
+ (Class)layerClass
{
return [CAShapeLayer class];
}
- (id)initWithFrame:(CGRect)frame
{
self = [super initWithFrame:frame];
if (self) {
[self setupLayer];
}
return self;
}
/* Create the tennis ball */
- (void)setupLayer
{
CAShapeLayer *layer = (CAShapeLayer *)self.layer;
layer.strokeColor = [[UIColor blackColor] CGColor];
layer.fillColor = [[UIColor yellowColor] CGColor];
layer.lineWidth = 1.5;
layer.path = [self defaultPath];
}
/* Animate the tennis ball "bouncing" off of the side of the screen */
- (void)bounce
{
CABasicAnimation *animation = [CABasicAnimation animationWithKeyPath:#"path"];
animation.duration = 0.2;
animation.timingFunction = [CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionEaseInEaseOut];
animation.fromValue = (__bridge id)[self defaultPath];
animation.toValue = (__bridge id)[self compressedPath];
animation.autoreverses = YES;
[self.layer addAnimation:animation forKey:#"animatePath"];
}
/* A path representing the tennis ball in the default state */
- (CGPathRef)defaultPath
{
return [[UIBezierPath bezierPathWithOvalInRect:self.frame] CGPath];
}
/* A path representing the tennis ball is the compressed state (during the bounce) */
- (CGPathRef)compressedPath
{
CGRect newFrame = CGRectMake(self.frame.origin.x, self.frame.origin.y, self.frame.size.width * 0.85, self.frame.size.height);
return [[UIBezierPath bezierPathWithOvalInRect:newFrame] CGPath];
}
#end
Now, when you want to use this:
TennisBall *ball = [[TennisBall alloc] initWithFrame:CGRectMake(10, 10, 100, 100)];
[self.view addSubview:ball];
[ball bounce];
Note that this will need to be extended so that you can "bounce" from different angles, etc. but it should get you pointed in the right direction!
I want to do something similar to the following:
How to mask an image in IOS sdk?
I want to cover the entire screen with translucent black. Then, I want to cut a circle out of the translucent black covering so that you can see through clearly. I'm doing this to highlight parts of the screen for a tutorial.
I then want to animate the cut-out circle to other parts of the screen. I also want to be able to stretch the cut-out circle horizontally & vertically, as you would do with a generic button background image.
(UPDATE: Please see also my other answer which describes how to set up multiple independent, overlapping holes.)
Let's use a plain old UIView with a backgroundColor of translucent black, and give its layer a mask that cuts a hole out of the middle. We'll need an instance variable to reference the hole view:
#implementation ViewController {
UIView *holeView;
}
After loading the main view, we want to add the hole view as a subview:
- (void)viewDidLoad {
[super viewDidLoad];
[self addHoleSubview];
}
Since we want to move the hole around, it will be convenient to make the hole view be very large, so that it covers the rest of the content regardless of where it's positioned. We'll make it 10000x10000. (This doesn't take up any more memory because iOS doesn't automatically allocate a bitmap for the view.)
- (void)addHoleSubview {
holeView = [[UIView alloc] initWithFrame:CGRectMake(0, 0, 10000, 10000)];
holeView.backgroundColor = [UIColor colorWithWhite:0.0 alpha:0.5];
holeView.autoresizingMask = 0;
[self.view addSubview:holeView];
[self addMaskToHoleView];
}
Now we need to add the mask that cuts a hole out of the hole view. We'll do this by creating a compound path consisting of a huge rectangle with a smaller circle at its center. We'll fill the path with black, leaving the circle unfilled and therefore transparent. The black part has alpha=1.0 and so it makes the hole view's background color show. The transparent part has alpha=0.0, so that part of the hole view is also transparent.
- (void)addMaskToHoleView {
CGRect bounds = holeView.bounds;
CAShapeLayer *maskLayer = [CAShapeLayer layer];
maskLayer.frame = bounds;
maskLayer.fillColor = [UIColor blackColor].CGColor;
static CGFloat const kRadius = 100;
CGRect const circleRect = CGRectMake(CGRectGetMidX(bounds) - kRadius,
CGRectGetMidY(bounds) - kRadius,
2 * kRadius, 2 * kRadius);
UIBezierPath *path = [UIBezierPath bezierPathWithOvalInRect:circleRect];
[path appendPath:[UIBezierPath bezierPathWithRect:bounds]];
maskLayer.path = path.CGPath;
maskLayer.fillRule = kCAFillRuleEvenOdd;
holeView.layer.mask = maskLayer;
}
Notice that I've put the circle at the center of the 10000x10000 view. This means that we can just set holeView.center to set the center of the circle relative to the other content. So, for example, we can easily animate it up and down over the main view:
- (void)viewDidLayoutSubviews {
CGRect const bounds = self.view.bounds;
holeView.center = CGPointMake(CGRectGetMidX(bounds), 0);
// Defer this because `viewDidLayoutSubviews` can happen inside an
// autorotation animation block, which overrides the duration I set.
dispatch_async(dispatch_get_main_queue(), ^{
[UIView animateWithDuration:2 delay:0
options:UIViewAnimationOptionRepeat
| UIViewAnimationOptionAutoreverse
animations:^{
holeView.center = CGPointMake(CGRectGetMidX(bounds),
CGRectGetMaxY(bounds));
} completion:nil];
});
}
Here's what it looks like:
But it's smoother in real life.
You can find a complete working test project in this github repository.
This is not a simple one. I can get you a good bit of the way there. It's the animating that is tricky. Here's the output of some code I threw together:
The code is like this:
- (void)viewDidLoad
{
[super viewDidLoad];
// Create a containing layer and set it contents with an image
CALayer *containerLayer = [CALayer layer];
[containerLayer setBounds:CGRectMake(0.0f, 0.0f, 500.0f, 320.0f)];
[containerLayer setPosition:[[self view] center]];
UIImage *image = [UIImage imageNamed:#"cool"];
[containerLayer setContents:(id)[image CGImage]];
// Create your translucent black layer and set its opacity
CALayer *translucentBlackLayer = [CALayer layer];
[translucentBlackLayer setBounds:[containerLayer bounds]];
[translucentBlackLayer setPosition:
CGPointMake([containerLayer bounds].size.width/2.0f,
[containerLayer bounds].size.height/2.0f)];
[translucentBlackLayer setBackgroundColor:[[UIColor blackColor] CGColor]];
[translucentBlackLayer setOpacity:0.45];
[containerLayer addSublayer:translucentBlackLayer];
// Create a mask layer with a shape layer that has a circle path
CAShapeLayer *maskLayer = [CAShapeLayer layer];
[maskLayer setBorderColor:[[UIColor purpleColor] CGColor]];
[maskLayer setBorderWidth:5.0f];
[maskLayer setBounds:[containerLayer bounds]];
// When you create a path, remember that origin is in upper left hand
// corner, so you have to treat it as if it has an anchor point of 0.0,
// 0.0
UIBezierPath *path = [UIBezierPath bezierPathWithOvalInRect:
CGRectMake([translucentBlackLayer bounds].size.width/2.0f - 100.0f,
[translucentBlackLayer bounds].size.height/2.0f - 100.0f,
200.0f, 200.0f)];
// Append a rectangular path around the mask layer so that
// we can use the even/odd fill rule to invert the mask
[path appendPath:[UIBezierPath bezierPathWithRect:[maskLayer bounds]]];
// Set the path's fill color since layer masks depend on alpha
[maskLayer setFillColor:[[UIColor blackColor] CGColor]];
[maskLayer setPath:[path CGPath]];
// Center the mask layer in the translucent black layer
[maskLayer setPosition:
CGPointMake([translucentBlackLayer bounds].size.width/2.0f,
[translucentBlackLayer bounds].size.height/2.0f)];
// Set the fill rule to even odd
[maskLayer setFillRule:kCAFillRuleEvenOdd];
// Set the translucent black layer's mask property
[translucentBlackLayer setMask:maskLayer];
// Add the container layer to the view so we can see it
[[[self view] layer] addSublayer:containerLayer];
}
You would have to animate the mask layer which you could build up based on user input, but it will be a bit challenging. Notice the lines where I append a rectangular path to the circle path and then set the fill rule a few lines later on the shape layer. These are what make the inverted mask possible. If you leave those out you will instead show the translucent black in the center of the circle and then nothing on the outer part (if that makes sense).
Maybe try to play with this code a bit and see if you can get it animating. I'll play with it some more as I have time, but this is a pretty interesting problem. Would love to see a complete solution.
UPDATE: So here's another stab at it. The trouble here is that this one makes the translucent mask look white instead of black, but the upside is that circle can be animated pretty easily.
This one builds up a composite layer with the translucent layer and the circle layer being siblings inside of a parent layer that gets used as the mask.
I added a basic animation to this one so we could see the circle layer animate.
- (void)viewDidLoad
{
[super viewDidLoad];
CGRect baseRect = CGRectMake(0.0f, 0.0f, 500.0f, 320.0f);
CALayer *containerLayer = [CALayer layer];
[containerLayer setBounds:baseRect];
[containerLayer setPosition:[[self view] center]];
UIImage *image = [UIImage imageNamed:#"cool"];
[containerLayer setContents:(id)[image CGImage]];
CALayer *compositeMaskLayer = [CALayer layer];
[compositeMaskLayer setBounds:baseRect];
[compositeMaskLayer setPosition:CGPointMake([containerLayer bounds].size.width/2.0f, [containerLayer bounds].size.height/2.0f)];
CALayer *translucentLayer = [CALayer layer];
[translucentLayer setBounds:baseRect];
[translucentLayer setBackgroundColor:[[UIColor blackColor] CGColor]];
[translucentLayer setPosition:CGPointMake([containerLayer bounds].size.width/2.0f, [containerLayer bounds].size.height/2.0f)];
[translucentLayer setOpacity:0.35];
[compositeMaskLayer addSublayer:translucentLayer];
CAShapeLayer *circleLayer = [CAShapeLayer layer];
UIBezierPath *circlePath = [UIBezierPath bezierPathWithOvalInRect:CGRectMake(0.0f, 0.0f, 200.0f, 200.0f)];
[circleLayer setBounds:CGRectMake(0.0f, 0.0f, 200.0f, 200.0f)];
[circleLayer setPosition:CGPointMake([containerLayer bounds].size.width/2.0f, [containerLayer bounds].size.height/2.0f)];
[circleLayer setPath:[circlePath CGPath]];
[circleLayer setFillColor:[[UIColor blackColor] CGColor]];
[compositeMaskLayer addSublayer:circleLayer];
[containerLayer setMask:compositeMaskLayer];
[[[self view] layer] addSublayer:containerLayer];
CABasicAnimation *posAnimation = [CABasicAnimation animationWithKeyPath:#"position"];
[posAnimation setFromValue:[NSValue valueWithCGPoint:[circleLayer position]]];
[posAnimation setToValue:[NSValue valueWithCGPoint:CGPointMake([circleLayer position].x + 100.0f, [circleLayer position].y + 100)]];
[posAnimation setDuration:1.0f];
[posAnimation setRepeatCount:INFINITY];
[posAnimation setAutoreverses:YES];
[circleLayer addAnimation:posAnimation forKey:#"position"];
}
Here's an answer that works with multiple independent, possibly overlapping spotlights.
I'll set up my view hierarchy like this:
SpotlightsView with black background
UIImageView with `alpha`=.5 (“dim view”)
UIImageView with shape layer mask (“bright view”)
The dim view will appear dimmed because its alpha mixes its image with the black of the top-level view.
The bright view is not dimmed, but it only shows where its mask lets it. So I just set the mask to contain the spotlight areas and nowhere else.
Here's what it looks like:
I'll implement it as a subclass of UIView with this interface:
// SpotlightsView.h
#import <UIKit/UIKit.h>
#interface SpotlightsView : UIView
#property (nonatomic, strong) UIImage *image;
- (void)addDraggableSpotlightWithCenter:(CGPoint)center radius:(CGFloat)radius;
#end
I'll need QuartzCore (also called Core Animation) and the Objective-C runtime to implement it:
// SpotlightsView.m
#import "SpotlightsView.h"
#import <QuartzCore/QuartzCore.h>
#import <objc/runtime.h>
I'll need instance variables for the subviews, the mask layer, and an array of individual spotlight paths:
#implementation SpotlightsView {
UIImageView *_dimImageView;
UIImageView *_brightImageView;
CAShapeLayer *_mask;
NSMutableArray *_spotlightPaths;
}
To implement the image property, I just pass it through to your image subviews:
#pragma mark - Public API
- (void)setImage:(UIImage *)image {
_dimImageView.image = image;
_brightImageView.image = image;
}
- (UIImage *)image {
return _dimImageView.image;
}
To add a draggable spotlight, I create a path outlining the spotlight, add it to the array, and flag myself as needing layout:
- (void)addDraggableSpotlightWithCenter:(CGPoint)center radius:(CGFloat)radius {
UIBezierPath *path = [UIBezierPath bezierPathWithOvalInRect:CGRectMake(center.x - radius, center.y - radius, 2 * radius, 2 * radius)];
[_spotlightPaths addObject:path];
[self setNeedsLayout];
}
I need to override some methods of UIView to handle initialization and layout. I'll handle being created either programmatically or in a xib or storyboard by delegating the common initialization code to a private method:
#pragma mark - UIView overrides
- (instancetype)initWithFrame:(CGRect)frame
{
if (self = [super initWithFrame:frame]) {
[self commonInit];
}
return self;
}
- (instancetype)initWithCoder:(NSCoder *)aDecoder {
if (self = [super initWithCoder:aDecoder]) {
[self commonInit];
}
return self;
}
I'll handle layout in separate helper methods for each subview:
- (void)layoutSubviews {
[super layoutSubviews];
[self layoutDimImageView];
[self layoutBrightImageView];
}
To drag the spotlights when they are touched, I need to override some UIResponder methods. I want to handle each touch separately, so I just loop over the updated touches, passing each one to a helper method:
#pragma mark - UIResponder overrides
- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event {
for (UITouch *touch in touches){
[self touchBegan:touch];
}
}
- (void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event {
for (UITouch *touch in touches){
[self touchMoved:touch];
}
}
- (void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event {
for (UITouch *touch in touches) {
[self touchEnded:touch];
}
}
- (void)touchesCancelled:(NSSet *)touches withEvent:(UIEvent *)event {
for (UITouch *touch in touches) {
[self touchEnded:touch];
}
}
Now I'll implement the private appearance and layout methods.
#pragma mark - Implementation details - appearance/layout
First I'll do the common initialization code. I want to set my background color to black, since that is part of making the dimmed image view dim, and I want to support multiple touches:
- (void)commonInit {
self.backgroundColor = [UIColor blackColor];
self.multipleTouchEnabled = YES;
[self initDimImageView];
[self initBrightImageView];
_spotlightPaths = [NSMutableArray array];
}
My two image subviews will be configured mostly the same way, so I'll call another private method to create the dim image view, then tweak it to actually be dim:
- (void)initDimImageView {
_dimImageView = [self newImageSubview];
_dimImageView.alpha = 0.5;
}
I'll call the same helper method to create the bright view, then add its mask sublayer:
- (void)initBrightImageView {
_brightImageView = [self newImageSubview];
_mask = [CAShapeLayer layer];
_brightImageView.layer.mask = _mask;
}
The helper method that creates both image views sets the content mode and adds the new view as a subview:
- (UIImageView *)newImageSubview {
UIImageView *subview = [[UIImageView alloc] init];
subview.contentMode = UIViewContentModeScaleAspectFill;
[self addSubview:subview];
return subview;
}
To lay out the dim image view, I just need to set its frame to my bounds:
- (void)layoutDimImageView {
_dimImageView.frame = self.bounds;
}
To lay out the bright image view, I need to set its frame to my bounds, and I need to update its mask layer's path to be the union of the individual spotlight paths:
- (void)layoutBrightImageView {
_brightImageView.frame = self.bounds;
UIBezierPath *unionPath = [UIBezierPath bezierPath];
for (UIBezierPath *path in _spotlightPaths) {
[unionPath appendPath:path];
}
_mask.path = unionPath.CGPath;
}
Note that this isn't a true union that encloses each point once. It relies on the fill mode (the default, kCAFillRuleNonZero) to ensure that repeatedly-enclosed points are included in the mask.
Next up, touch handling.
#pragma mark - Implementation details - touch handling
When UIKit sends me a new touch, I'll find the individual spotlight path containing the touch, and attach the path to the touch as an associated object. That means I need an associated object key, which just needs to be some private thing I can take the address of:
static char kSpotlightPathAssociatedObjectKey;
Here I actually find the path and attach it to the touch. If the touch is outside any of my spotlight paths, I ignore it:
- (void)touchBegan:(UITouch *)touch {
UIBezierPath *path = [self firstSpotlightPathContainingTouch:touch];
if (path == nil)
return;
objc_setAssociatedObject(touch, &kSpotlightPathAssociatedObjectKey,
path, OBJC_ASSOCIATION_RETAIN_NONATOMIC);
}
When UIKit tells me a touch has moved, I see if the touch has a path attached. If so, I translate (slide) the path by the amount that the touch has moved since I last saw it. Then I flag myself for layout:
- (void)touchMoved:(UITouch *)touch {
UIBezierPath *path = objc_getAssociatedObject(touch,
&kSpotlightPathAssociatedObjectKey);
if (path == nil)
return;
CGPoint point = [touch locationInView:self];
CGPoint priorPoint = [touch previousLocationInView:self];
[path applyTransform:CGAffineTransformMakeTranslation(
point.x - priorPoint.x, point.y - priorPoint.y)];
[self setNeedsLayout];
}
I don't actually need to do anything when the touch ends or is cancelled. The Objective-C runtime will de-associated the attached path (if there is one) automatically:
- (void)touchEnded:(UITouch *)touch {
// Nothing to do
}
To find the path that contains a touch, I just loop over the spotlight paths, asking each one if it contains the touch:
- (UIBezierPath *)firstSpotlightPathContainingTouch:(UITouch *)touch {
CGPoint point = [touch locationInView:self];
for (UIBezierPath *path in _spotlightPaths) {
if ([path containsPoint:point])
return path;
}
return nil;
}
#end
I have uploaded a full demo to github.
I've been struggling with this same problem and found some great help here on SO so I thought I'd share my solution combining a few different ideas I found online. One additional feature I added was for the cut-out to have a gradient effect. The added benefit to this solution is that it works with any UIView and not just with images.
First subclass UIView to black out everything except the frames you want cut out:
// BlackOutView.h
#interface BlackOutView : UIView
#property (nonatomic, retain) UIColor *fillColor;
#property (nonatomic, retain) NSArray *framesToCutOut;
#end
// BlackOutView.m
#implementation BlackOutView
- (void)drawRect:(CGRect)rect
{
CGContextRef context = UIGraphicsGetCurrentContext();
CGContextSetBlendMode(context, kCGBlendModeDestinationOut);
for (NSValue *value in self.framesToCutOut) {
CGRect pathRect = [value CGRectValue];
UIBezierPath *path = [UIBezierPath bezierPathWithRect:pathRect];
// change to this path for a circular cutout if you don't want a gradient
// UIBezierPath *path = [UIBezierPath bezierPathWithOvalInRect:pathRect];
[path fill];
}
CGContextSetBlendMode(context, kCGBlendModeNormal);
}
#end
If you don't want the blur effect, then you can swap paths to the oval one and skip the blur mask below. Otherwise, the cutout will be square and filled with a circular gradient.
Create a gradient shape with the center transparent and slowly fading in black:
// BlurFilterMask.h
#interface BlurFilterMask : CAShapeLayer
#property (assign) CGPoint origin;
#property (assign) CGFloat diameter;
#property (assign) CGFloat gradient;
#end
// BlurFilterMask.m
#implementation CRBlurFilterMask
- (void)drawInContext:(CGContextRef)context
{
CGFloat gradientWidth = self.diameter * 0.5f;
CGFloat clearRegionRadius = self.diameter * 0.25f;
CGFloat blurRegionRadius = clearRegionRadius + gradientWidth;
CGColorSpaceRef baseColorSpace = CGColorSpaceCreateDeviceRGB();
CGFloat colors[8] = { 0.0f, 0.0f, 0.0f, 0.0f, // Clear region colour.
0.0f, 0.0f, 0.0f, self.gradient }; // Blur region colour.
CGFloat colorLocations[2] = { 0.0f, 0.4f };
CGGradientRef gradient = CGGradientCreateWithColorComponents (baseColorSpace, colors, colorLocations, 2);
CGContextDrawRadialGradient(context, gradient, self.origin, clearRegionRadius, self.origin, blurRegionRadius, kCGGradientDrawsAfterEndLocation);
CGColorSpaceRelease(baseColorSpace);
CGGradientRelease(gradient);
}
#end
Now you just need to call these two together and pass in the UIViews that you want cutout
- (void)viewWillAppear:(BOOL)animated
{
[super viewWillAppear:animated];
[self addMaskInViews:#[self.viewCutout1, self.viewCutout2]];
}
- (void) addMaskInViews:(NSArray *)viewsToCutOut
{
NSMutableArray *frames = [NSMutableArray new];
for (UIView *view in viewsToCutOut) {
view.hidden = YES; // hide the view since we only use their bounds
[frames addObject:[NSValue valueWithCGRect:view.frame]];
}
// Create the overlay passing in the frames we want to cut out
BlackOutView *overlay = [[BlackOutView alloc] initWithFrame:self.view.frame];
overlay.backgroundColor = [UIColor colorWithWhite:0.0 alpha:0.8];
overlay.framesToCutOut = frames;
[self.view insertSubview:overlay atIndex:0];
// add a circular gradients inside each view
for (UIView *maskView in viewsToCutOut)
{
BlurFilterMask *blurFilterMask = [BlurFilterMask layer];
blurFilterMask.frame = maskView.frame;
blurFilterMask.gradient = 0.8f;
blurFilterMask.diameter = MIN(maskView.frame.size.width, maskView.frame.size.height);
blurFilterMask.origin = CGPointMake(maskView.frame.size.width / 2, maskView.frame.size.height / 2);
[self.view.layer addSublayer:blurFilterMask];
[blurFilterMask setNeedsDisplay];
}
}
If you just want something that is plug and play, I added a library to CocoaPods that allows you to create overlays with rectangular/circular holes, allowing the user to interact with views behind the overlay. It is a Swift implementation of similar strategies used in other answers. I used it to create this tutorial for one of our apps:
The library is called TAOverlayView, and is open source under Apache 2.0.
Note: I haven't implemented moving holes yet (unless you move the entire overlay as in other answers).