I have a UITableViewCell subclass which overrides layoutSubviews to apply a fade effect to a webview. For the most part it works fine, but sometimes it ends up in a state where layoutSubvies is called constantly with alternating values for the content height for the webview.
Is there some other place I could apply this gradient to avoid this issue?
CAGradientLayer* gradientLayer = nil;
int webViewHeight = 0;
- (void)layoutSubviews
{
NSLog(#"layoutSubviews %f", self.webView.scrollView.contentSize.height);
[super layoutSubviews];
if (self.webView.scrollView.contentSize.height == webViewHeight) {
// nothing has changed
return;
}
if (gradientLayer != nil) {
[gradientLayer removeFromSuperlayer];
gradientLayer = nil;
}
// if cell height is less than web view height we must fade
if (self.frame.size.height < self.webView.scrollView.contentSize.height) {
webViewHeight = self.webView.scrollView.contentSize.height;
gradientLayer = [CAGradientLayer layer];
NSObject* fadeColor = (NSObject*)[UIColor colorWithWhite:1.0 alpha:.9].CGColor;
NSObject* transparentColor = (NSObject*)[UIColor colorWithWhite:1.0 alpha:0.0].CGColor;
gradientLayer.colors = [NSArray arrayWithObjects:transparentColor, fadeColor, nil];
gradientLayer.locations = [NSArray arrayWithObjects:
[NSNumber numberWithFloat:0.5],
[NSNumber numberWithFloat:1.0], nil];
gradientLayer.bounds = self.bounds;
gradientLayer.anchorPoint = CGPointZero;
[self.layer addSublayer:gradientLayer];
}
}
my TWO cents for similar issue. Hope can help others.
After debugging a little, I noted ALSO adding CALayer will re-invoke layoutSubviews
So if You call:
self.layer.addSublayer(anotherLayer)
you wil be re-called in layoutSubviews.
Related
I have a problem with my background gradient on my app. I set in viewDidLoad in MainViewController.
CAGradientLayer *bgLayer = [BackgroundGradient blackGradient];
bgLayer.frame = self.view.bounds;
[self.view.layer insertSublayer:bgLayer atIndex:0];
and every UIViewController extends from MainViewController. It works fine but after rotate device it show me only half background. Other is white. Can you help? Where can be the problem and show me it only half after rotate?
In BackgroundGradient.m
#implementation BackgroundGradient
+ (CAGradientLayer*) blackGradient {
UIColor *colorOne = [UIColor colorWithRed:0.12 green:0.13 blue:0.13 alpha:1.0];
UIColor *colorTwo = [UIColor colorWithRed:0.11 green:0.12 blue:0.13 alpha:1.0];
NSArray *colors = [NSArray arrayWithObjects:(id)colorOne.CGColor, colorTwo.CGColor, nil];
NSNumber *stopOne = [NSNumber numberWithFloat:0.0];
NSNumber *stopTwo = [NSNumber numberWithFloat:1.0];
NSArray *locations = [NSArray arrayWithObjects:stopOne, stopTwo, nil];
CAGradientLayer *headerLayer = [CAGradientLayer layer];
headerLayer.colors = colors;
headerLayer.locations = locations;
return headerLayer;
}
Save your layer into controller property, than override layoutSubviews method and update layer frame.
- (void)layoutSubviews {
[super layoutSubviews];
self.backgroundLayer.frame = self.view.bounds;
}
I use the following method to add some gradient effect to my IOS UIButton. I call it in viewController's viewDidLoad, works great, so far so good.
Now, I'd like to change the color of the button according to some user interaction. What I do is simply calling this method by different colors (fromColor, toColor) as input. The problem, the look of my button does not change. I tried to call setNeedsDisplay, but did not help.
Would you be so kind to help me? What I miss? There is should be some problem with layers, should be rested or something like that, but I could not find its proper way.
Update: By using setSubLayers instead of insertSubLayer color changes, but button title disappears.
+(void)setCustomButtonStyle:(UIButton *)button cornerRadius:(float) cornerRadius fromColor:(UIColor *)fromColor toColor:(UIColor *)toColor normalTitleColor:(UIColor *)normalTitleColor highlightedTitleColor:(UIColor *)highlightedTitleColor borderWidth:(float) borderWidth borderColor:(UIColor*)borderColor
{
[button setTitleColor:normalTitleColor forState:UIControlStateNormal];
[button setTitleColor:highlightedTitleColor forState:UIControlStateHighlighted];
CAGradientLayer *btnGradient = [CAGradientLayer layer];
btnGradient.frame = button.bounds;
btnGradient.colors = [NSArray arrayWithObjects:
(id)[fromColor CGColor],
(id)[toColor CGColor],
nil];
btnGradient.borderWidth = borderWidth;
btnGradient.borderColor = [borderColor CGColor];
[button.layer insertSublayer:btnGradient atIndex:0];
CALayer *btnLayer = [button layer];
[btnLayer setMasksToBounds:YES];
[btnLayer setCornerRadius:cornerRadius];
}
The problem you are having here is that 1. you are creating a new layer each time you are changing the colour and 2. you are then placing that new layer underneath everything else so you can't see it anyway. (Think of putting a playing card at the bottom of the deck).
What you need to do is keep hold of the gradient layer and then update then instead of creating a new one.
You are probably best doing this in a category on UIButton.
Something like... UIButton+GradientBackground or something.
In the .h file give it a single function...
// Use CGFloat not float. Also user NSInteger not int.
// Always.
// Also, I have used modern Obj-C syntax. Use this too.
- (void)setCornerRadius:(CGFloat)cornerRadius
fromColor:(UIColor *)fromColor
toColor:(UIColor *)toColor
normalTitleColor:(UIColor *)normalTitleColor
highlightedTitleColor:(UIColor *)highlightedTitleColor
borderWidth:(CGFloat)borderWidth
borderColor:(UIColor *)borderColor;
Then in the .m file you need to also give it a property...
#property (nonatomic, strong) CAGradientLayer *gradientLayer;
Now in the function...
- (void)setCornerRadius:(CGFloat)cornerRadius
fromColor:(UIColor *)fromColor
toColor:(UIColor *)toColor
normalTitleColor:(UIColor *)normalTitleColor
highlightedTitleColor:(UIColor *)highlightedTitleColor
borderWidth:(CGFloat)borderWidth
borderColor:(UIColor *)borderColor
{
[self setTitleColor:normalTitleColor forState:UIControlStateNormal];
[self setTitleColor:highlightedTitleColor forState:UIControlStateHighlighted];
if (!self.grandientLayer) {
// if it doesn't exist then create it and add it (only once)
self.gradientLayer = [CAGradientLayer layer];
[self.layer insertSublayer:self.gradientLayer atIndex:0];
}
self.gradientLayer.frame = self.bounds;
self.gradientLayer.colors = #[(id)fromColor.CGColor, (id)toColor.CGColor]; // use modern syntax
self.gradientLayer.borderWidth = borderWidth;
self.gradientLayer.borderColor = borderColor.CGColor;
[self.layer setMasksToBounds:YES];
[self.layer setCornerRadius:cornerRadius];
}
Notice that I have removed the button from the function name as this function will essentially be part of that UIButton's functions so self is the button you are changing.
You would call it like this...
[someButton setCornerRadius:5 fromColor:[UIColor redColor] toColor... and so on];
By doing this you only create that gradient layer once and you keep hold of it so that you can update it the next time round.
For first time add gradient layer, next time replace added gradient layer
Added Category as #Fogmeister thinks this can be used with category only
#interface UIButton (gradient)
+(void)setCustomButtonStyle:(UIButton *)button cornerRadius:(float) cornerRadius fromColor:(UIColor *)fromColor toColor:(UIColor *)toColor normalTitleColor:(UIColor *)normalTitleColor highlightedTitleColor:(UIColor *)highlightedTitleColor borderWidth:(float) borderWidth borderColor:(UIColor*)borderColor;
#end
#implementation UIButton (gradient)
+(void)setCustomButtonStyle:(UIButton *)button cornerRadius:(float) cornerRadius fromColor:(UIColor *)fromColor toColor:(UIColor *)toColor normalTitleColor:(UIColor *)normalTitleColor highlightedTitleColor:(UIColor *)highlightedTitleColor borderWidth:(float) borderWidth borderColor:(UIColor*)borderColor
{
//Set Title color as you want
[button setTitleColor:normalTitleColor forState:UIControlStateNormal];
[button setTitleColor:highlightedTitleColor forState:UIControlStateHighlighted];
//check gradientlayer exist
id layer = nil;
if (button.layer.sublayers.count > 0) {
layer = [button.layer.sublayers objectAtIndex:0];
}
//Find added gradient layer
CAGradientLayer *addedGradLayer = nil;
if (layer) {
if ([layer isKindOfClass:[CAGradientLayer class]]) {
addedGradLayer = (CAGradientLayer *)[button.layer.sublayers objectAtIndex:0];
}
}
//check gradient layer exists
if (!addedGradLayer) //first time
{
CAGradientLayer *gradientLayer = [CAGradientLayer layer];
gradientLayer.frame = button.layer.bounds;
gradientLayer.colors = [NSArray arrayWithObjects:
(id)fromColor.CGColor,
(id)toColor.CGColor,
nil];
gradientLayer.locations = [NSArray arrayWithObjects:
[NSNumber numberWithFloat:0.0f],
[NSNumber numberWithFloat:1.0f],
nil];
gradientLayer.cornerRadius = button.layer.cornerRadius;
[button.layer insertSublayer:gradientLayer atIndex:0];
button.clipsToBounds = YES;
}
else //next time
{
CAGradientLayer *newGradientLayer = [CAGradientLayer layer];
newGradientLayer.frame = button.layer.bounds;
newGradientLayer.colors = [NSArray arrayWithObjects:
(id)fromColor.CGColor,
(id)toColor.CGColor,
nil];
newGradientLayer.locations = [NSArray arrayWithObjects:
[NSNumber numberWithFloat:0.0f],
[NSNumber numberWithFloat:1.0f],
nil];
newGradientLayer.cornerRadius = button.layer.cornerRadius;
[button.layer replaceSublayer:addedGradLayer with:newGradientLayer];
}
}
#end
I'm developing an iOS app with latest SDK.
I want to change a background layer dynamically:
#import <QuartzCore/QuartzCore.h>
#interface MyClass : UIView
{
#private
CALayer* _gradientBackground;
}
And some methods:
- (CALayer*)createLayerWithColor:(UIColor*)color
{
CALayer* layer = [CALayer layer];
layer.frame = CGRectMake(NSLayerX, NSLayerY,
NSLayerWidth, NSLayerHeight);
layer.backgroundColor = [color CGColor];
layer.cornerRadius = NSCornerRadius;
return layer;
}
- (CAGradientLayer*)createLayerWithGradient:(UIColor*)startColor
endColor:(UIColor*)endColor
{
CAGradientLayer* gradientLayer = [CAGradientLayer layer];
gradientLayer.frame = CGRectMake(NSLayerX, NSLayerY,
NSLayerWidth, NSLayerHeight);
gradientLayer.colors =
[NSArray arrayWithObjects:(id)[startColor CGColor],
(id)[endColor CGColor], nil];
gradientLayer.cornerRadius = NSCornerRadius;
return gradientLayer;
}
- (void)changeBackgroundWithLayer:(CALayer*)newLayer
{
if (_gradientBackground != nil)
[_gradientBackground removeFromSuperlayer];
_gradientBackground = newLayer;
[self.layer insertSublayer:newLayer atIndex:0];
}
And I do this to change background layer:
[self changeBackgroundWithLayer:[self createLayerWithGradient:startColor endColor:endColor]];
And sometimes with this:
[self changeBackgroundWithLayer:[self createLayerWithColor:newColor]];
The way I do is:
First solid layer, next gradient layer and finally solid layer.
I have also tried with this code with no result:
- (void)changeBackgroundWithLayer:(CALayer*)newLayer
{
if (_gradientBackground != nil)
[self.layer replaceSublayer:_gradientBackground with:newLayer];
else
[self.layer insertSublayer:newLayer atIndex:0];
_gradientBackground = newLayer;
}
But it doesn't work.
Any advice?
Try this
- (void)changeBackgroundWithLayer:(CALayer*)newLayer
{
[_gradientBackground removeFromSuperlayer], _gradientBackground = nil;
[self.layer insertSublayer:newLayer atIndex:0];
_gradientBackground = newLayer;
}
This will remove the _gradientBackground and set it to nil in every case, which is perfectly acceptable in Objective-C. The newLayer is added to the layer hierarchy and the gradientBackground layer is updated.
I am customizing the UIButton with GradientLayer. I see a performance issue as view loading slowly and looks like a Jerk effect. Also when changing the orientation its same. I am using this code for an iPad application. With normal UIButton its smooth loading / rotating.
I am using the sample code found in google (GradientButton class) and is working fine. The container UIViewController which is pushed onto navigationcontroller stack to display the screen.
Here is the code:
- (void)awakeFromNib {
[self initLayers];
}
- (id)initWithFrame:(CGRect)frame {
if (self = [super initWithFrame:frame]) {
[self initLayers];
}
return self;
}
- (void)initLayers {
[self initBorder];
[self addShineLayer];
[self addHighlightLayer];
self.clipsToBounds = YES;
}
- (void)initBorder {
CALayer *layer = self.layer;
layer.cornerRadius = 8.0f;
layer.masksToBounds = YES;
layer.borderWidth = 1.0f;
layer.borderColor = [UIColor colorWithWhite:0.5f alpha:0.2f].CGColor;
}
- (void)addShineLayer {
shineLayer = [CAGradientLayer layer];
shineLayer.frame = self.layer.bounds;
shineLayer.colors = [NSArray arrayWithObjects:
(id)[UIColor colorWithWhite:1.0f alpha:0.4f].CGColor,
(id)[UIColor colorWithWhite:1.0f alpha:0.2f].CGColor,
(id)[UIColor colorWithWhite:0.75f alpha:0.2f].CGColor,
(id)[UIColor colorWithWhite:0.4f alpha:0.2f].CGColor,
(id)[UIColor colorWithWhite:1.0f alpha:0.4f].CGColor,
nil];
shineLayer.locations = [NSArray arrayWithObjects:
[NSNumber numberWithFloat:0.0f],
[NSNumber numberWithFloat:0.5f],
[NSNumber numberWithFloat:0.5f],
[NSNumber numberWithFloat:0.8f],
[NSNumber numberWithFloat:1.0f],
nil];
// shineLayer.shouldRasterize = YES;
// shineLayer.rasterizationScale = [UIScreen mainScreen].scale;
[self.layer addSublayer:shineLayer];
}
#pragma mark -
#pragma mark Highlight button while touched
- (void)addHighlightLayer {
highlightLayer = [CALayer layer];
highlightLayer.backgroundColor = [UIColor colorWithRed:0.25f green:0.25f blue:0.25f alpha:0.75].CGColor;
highlightLayer.frame = self.layer.bounds;
highlightLayer.hidden = YES;
[self.layer insertSublayer:highlightLayer below:shineLayer];
}
- (void)setHighlighted:(BOOL)highlight {
highlightLayer.hidden = !highlight;
[super setHighlighted:highlight];
}
Is the performance issue due to Gradient Layer ?? Please tell me how to rectify this issue.
Try commenting out the different property assignments in your code one at a time and see if you get any performance benefit. I worked on an app once that was getting about 12FPS in core animation when I used setCornerRadius on the layer compared to nearly full frame rate when I turned that off. The issue may be your gradient, however, you won't know for sure unless you just do some a/b comparisons turning off/on the various properties.
I'll tell you right now, though, that when I've used gradient layers on buttons in table view cells, I was able to speed up the table scrolling dramatically when I just used a background image for the button instead of a gradient layer. You can try to turn on shouldRasterize, however, make sure you do that at the top level of your layer tree and not on any sublayers (although the issues that I saw with setting that parameter on all layers may have been fixed in iOS6. I just haven't tested it).
I have a function that looks something like this:
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
// instantiate the cell
if(indexPath.row >=4 && indexPath.row <=5)
{
[CustomTableCell addGradient];
}
}
So basically, only rows 4 and 5 should have a gradient background. When the tableview first loads up, rows only rows 0 to 4 are visible and don't have gradient background which is perfect. When I scroll a little down to see rows 4 and 5, the gradient appears on them, which is great again. but when I scroll back up to the first row, all of a sudden i see a gradient on the first row!!! But i never asked row 0 to have a gradient! Additionally, when i scroll down a bit, i see gradients applied to some rows and not others. Why is this happening?
here's the addGradient function incase it's useful:
- (void) addGradient
{
if([self.layer.sublayers count] >0)
{
if([[self.layer.sublayers objectAtIndex:0] isKindOfClass:[CAGradientLayer class]])
return;
}
CAGradientLayer *gradient = [CAGradientLayer layer];
gradient.frame = self.bounds;
gradient.colors = [NSArray arrayWithObjects:(id)[UIColor blueColor].CGColor, (id)[UIColor redColor].CGColor, nil];
[self.layer insertSublayer:gradient atIndex:0];
}
I just realized that iPhone/cocoa is actually re-using an existing cell in memory for cellForRowAtIndexpath to draw cells that appear on screen. So that's why the cell still has a gradient layer I had set before. So i updated my stylecell function to remove a layer if it exists, by using this code:
- (void) styleCell
{
if([self.layer.sublayers count] >0)
{
if([[self.layer.sublayers objectAtIndex:0] isKindOfClass:[CAGradientLayer class]])
{
[[self.layer.sublayers objectAtIndex:0] removeFromSuperlayer];
// return;
}
}
CAGradientLayer *gradient = [CAGradientLayer layer];
gradient.frame = self.bounds;
gradient.colors = [NSArray arrayWithObjects:(id)[UIColor blueColor].CGColor, (id)[UIColor redColor].CGColor, nil];
[self.layer insertSublayer:gradient atIndex:0];
}
#end