Undo Button Swift - ios

I have a drawing app that uses CALayer sublayers for the actual drawing of an image. I currently have an IBAction that contains code to remove the sublayers from the superlayer. However everytime I run it, I get a BAD ACCESS error that crashes my app. I'm wondering why it won't allow me to remove the sublayers. Also, in theory, this approach would remove all of the layers entirely. I would ideally want it to only undo the last layers that were drawn. Any suggestions on what I should do? Thanks.
var locale: CALayer {
return layerView.layer
}
#IBAction func undoButton(sender: AnyObject) {
var sublayers = self.view.layer.sublayers
for layer in sublayers {
layer.removeFromSuperlayer()
}
}
func setUpLayer() -> CALayer {
locale.contents = image
locale.contentsGravity = kCAGravityCenter
return locale
}
func subLayerDisplay() {
var newLayer = CALayer()
var tempRect = CGRectMake(prevLocation.x, prevLocation.y, 50, 50)
newLayer.frame = tempRect
newLayer.contents = image
self.view.layer.insertSublayer(newLayer, below: locale)
}

To sum up, you can add your layer to a view, and then deal with the view, which will make life much more easier.
When you add the button, you can do
view.tag = 1
self.addSubView(view)
When you want to remove it
let view = self.viewWithTag(1) as! UIView
view.removeFromSuperView()

Related

Is it possible to group images by drawing lines on it in iOS swift?

For an example if i have multiple images on views in random position. Images are selected by drawing lines on it and group images by using gestures. Right now i can able to show images randomly but not able group images by drawing line on it.
Here screenshot 1 is result which i have getting now:
screenshot 2 which is exactly what i want.
For what you are trying to do I would start by creating a custom view (a subclass) that is able to handle gestures and draw paths.
For gesture recognizer I would use UIPanGestureRecognizer. What you do is have an array of points where the gesture was handled which are then used to draw the path:
private var currentPathPoints: [CGPoint] = []
#objc private func onPan(_ sender: UIGestureRecognizer) {
switch sender.state {
case .began: currentPathPoints = [sender.location(in: self)] // Reset current array by only showing a current point. User just started his path
case .changed: currentPathPoints.append(sender.location(in: self)) // Just append a new point
case .cancelled, .ended: endPath() // Will need to report that user lifted his finger
default: break // These extra states are her just to annoy us
}
}
So if this method is used by pan gesture recognizer it should track points where user is dragging. Now these are best drawn in drawRect which needs to be overridden in your view like:
override func draw(_ rect: CGRect) {
super.draw(rect)
// Generate path
let path: UIBezierPath = {
let path = UIBezierPath()
var pointsToDistribute = currentPathPoints
if let first = pointsToDistribute.first {
path.move(to: first)
pointsToDistribute.remove(at: 0)
}
pointsToDistribute.forEach { point in
path.addLine(to: point)
}
return path
}()
let color = UIColor.red // TODO: user your true color
color.setStroke()
path.lineWidth = 3.0
path.stroke()
}
Now this method will be called when you invalidate drawing by calling setNeedsDisplay. In your case that is best done on setter of your path points:
private var currentPathPoints: [CGPoint] = [] {
didSet {
setNeedsDisplay()
}
}
Since this view should be as an overlay to your whole scene you need some way to reporting the events back. A delegate procedure should be created that implements methods like:
func endPath() {
delegate?.myLineView(self, finishedPath: currentPathPoints)
}
So now if view controller is a delegate it can check which image views were selected within the path. For first version it should be enough to just check if any of the points is within any of the image views:
func myLineView(sender: MyLineView, finishedPath pathPoints: [CGPoint]) {
let convertedPoints: [CGPoint] = pathPoints.map { sender.convert($0, to: viewThatContainsImages) }
let imageViewsHitByPath = allImageViews.filter { imageView in
return convertedPoints.contains(where: { imageView.frame.contains($0) })
}
// Use imageViewsHitByPath
}
Now after this basic implementation you can start playing by drawing a nicer line (curved) and with cases where you don't check if a point is inside image view but rather if a line between any 2 neighbor points intersects your image view.

How can return UIView views along with its subviews in swift?

I want to create a stack of rounded circle views like this.
UIView stack
I want to return this whole stack of UIViews at once. So I tried in this way.
open func setupCirclestack(parentFrame:CGRect)->UIView
{
let arrayColor=[UIColor.yellow,UIColor.blue,UIColor.red]
let baseCircle=Circle.init(frame: parentFrame)
baseCircle.backgroundColor=UIColor.purple
var parentview=baseCircle
// var existingFrame=baseCircle.frame
for i in 0...2//<CircleValues().numberOfCircles-1
{
let circle=self.getInnerCircle(currentFrame: parentFrame)
circle.backgroundColor=arrayColor[i]
parentview.addSubview(circle)
parentview=circle as! Circle
//existingFrame=circle.frame
}
return parentview
}
func getInnerCircle(currentFrame:CGRect)->UIView
{
CircleValues.sharedInstance.radius=CircleValues.sharedInstance.radius-30
print("New Radius------\(CircleValues.sharedInstance.radius)")
let circle=Circle.init(frame: currentFrame)
return circle
}
But I can get only the last (inner most view) view. How can I return the whole stack of UIViews from this method
It is because your all the frames for all the circles are same as parentFrame.
So, your all views are adding but you can only able to see last view as it is overlaps other views!
You have to decrease your frame size for every iteration of your for loop for every child view you are adding!
for i in 0...2//<CircleValues().numberOfCircles-1
{
let circle=self.getInnerCircle(currentFrame: parentFrame) // decrease size(height and width) here every time to achieve result attached in screenshot in your question
circle.backgroundColor=arrayColor[i]
parentview.addSubview(circle)
parentview=circle as! Circle
//existingFrame=circle.frame
}
You reasign a parentView variable at the end of for loop, So it will replace existing object of parentView in which you added the circle as a subview. Therefore it will return a last circle object which is stored in parentView.
for i in 0...2//<CircleValues().numberOfCircles-1
{
let circle=self.getInnerCircle(currentFrame: parentFrame)
circle.backgroundColor=arrayColor[i]
parentview.addSubview(circle)
//parentview=circle as! Circle
//existingFrame=circle.frame
}
If you want to return views inside your parent view you need to change your function to something like this:
open func setupCirclestack(parentFrame:CGRect)->UIView
{
let arrayColor=[UIColor.yellow,UIColor.blue,UIColor.red]
let baseCircle=Circle.init(frame: parentFrame)
baseCircle.backgroundColor=UIColor.purple
var parentview=baseCircle
// var existingFrame=baseCircle.frame
for i in 0...2//<CircleValues().numberOfCircles-1
{
let circle=self.getInnerCircle(currentFrame: parentFrame)
circle.backgroundColor=arrayColor[i]
parentview.addSubview(circle)
}
return parentview
}
But if you need to return array of views, try this:
open func setupCirclestack(parentFrame:CGRect)->[UIView]
{
let arrayColor = [UIColor.yellow,UIColor.blue,UIColor.red]
let baseCircle = Circle.init(frame: parentFrame)
baseCircle.backgroundColor=UIColor.purple
var circleArray = [Circle]()
for i in 0...2
{
let circle = self.getInnerCircle(currentFrame: parentFrame)
circle.backgroundColor = arrayColor[i]
circleArray.append(circle)
}
return circleArray
}

removeFromSuperLayer occasionally not working for sub UIView on UICollectionViewCell iOS Swift

For an iOS app in Swift, I add a gradient layer to a UIView in a custom UICollectionViewCell Subclass with an extension method.
extension UIView {
func addGradientLayer() {
let color1 = Constants.Colors.gradientStart
let color2 = Constants.Colors.gradientEnd
let gradientLayer = CAGradientLayer()
gradientLayer.name = Constants.gradientLayerName
gradientLayer.frame = self.bounds
gradientLayer.colors = [color1.cgColor, color2.cgColor]
self.layer.insertSublayer(gradientLayer, at: 0)
}
}
I have two states for my UICollectionViewCell Subclass, either with a gradient layer or without.
if true { // bool statement
cell.listeningView.addGradientLayer()
} else {
if let layers = cell.listeningView.layer.sublayers {
for (index, layer) in layers.enumerated() {
if layer.name == Constants.gradientLayerName {
cell.listeningView.layer.sublayers?[index].removeFromSuperlayer()
break
}
}
}
cell.listeningView.backgroundColor = Constants.Colors.newsFeedItemNotInFocus
}
Occasionally when my cells are dequeuing the gradientLayer is unable to be removed, despite the removeFromSuperLayer method being called. Does anyone know why this is happening? and how I can ensure the layer gets removed?
The only reason would be that you are adding this sublayer more than once. Try to remove the break inside the loop and test it again.
Fast solution: remove the layer before adding it again.
if let layers = cell.listeningView.layer.sublayers {
for (index, layer) in layers.enumerated() {
if layer.name == Constants.gradientLayerName {
cell.listeningView.layer.sublayers?[index].removeFromSuperlayer()
//break with or without
}
}
}
cell.listeningView.addGradientLayer()
There is at least second reason for remove..() not working: if the code is executed not in the main thread. Then the call succeeds but there is no effect.

Circular (round) UIView resizing with AutoLayout... how to animate cornerRadius during the resize animation?

I have a subclassed UIView that we can call CircleView. CircleView automatically sets a corner radius to half of its width in order for it to be a circle.
The problem is that when "CircleView" is resized by an AutoLayout constraint... for example on a device rotation... it distorts badly until the resize takes place because the "cornerRadius" property has to catch up, and the OS only sends a single "bounds" change to the view's frame.
I was wondering if anyone had a good, clear strategy for implementing "CircleView" in a way that won't distort in such instances, but will still mask its contents to the shape of a circle and allow for a border to exist around said UIView.
UPDATE: If your deployment target is iOS 11 or later:
Starting in iOS 11, UIKit will animate cornerRadius if you update it inside an animation block. Just set your view's layer.cornerRadius in a UIView animation block, or (to handle interface orientation changes), set it in layoutSubviews or viewDidLayoutSubviews.
ORIGINAL: If your deployment target is older than iOS 11:
So you want this:
(I turned on Debug > Slow Animations to make the smoothness easier to see.)
Side rant, feel free to skip this paragraph: This turns out to be a lot harder than it should be, because the iOS SDK doesn't make the parameters (duration, timing curve) of the autorotation animation available in a convenient way. You can (I think) get at them by overriding -viewWillTransitionToSize:withTransitionCoordinator: on your view controller to call -animateAlongsideTransition:completion: on the transition coordinator, and in the callback you pass, get the transitionDuration and completionCurve from the UIViewControllerTransitionCoordinatorContext. And then you need to pass that information down to your CircleView, which has to save it (because it hasn't been resized yet!) and later when it receives layoutSubviews, it can use it to create a CABasicAnimation for cornerRadius with those saved animation parameters. And don't accidentally create an animation when it's not an animated resize… End of side rant.
Wow, that sounds like a ton of work, and you have to involve the view controller. Here's another approach that's entirely implemented inside CircleView. It works now (in iOS 9) but I can't guarantee it'll always work in the future, because it makes two assumptions that could theoretically be wrong in the future.
Here's the approach: override -actionForLayer:forKey: in CircleView to return an action that, when run, installs an animation for cornerRadius.
These are the two assumptions:
bounds.origin and bounds.size get separate animations. (This is true now but presumably a future iOS could use a single animation for bounds. It would be easy enough to check for a bounds animation if no bounds.size animation were found.)
The bounds.size animation is added to the layer before Core Animation asks for the cornerRadius action.
Given these assumptions, when Core Animation asks for the cornerRadius action, we can get the bounds.size animation from the layer, copy it, and modify the copy to animate cornerRadius instead. The copy has the same animation parameters as the original (unless we modify them), so it has the correct duration and timing curve.
Here's the start of CircleView:
class CircleView: UIView {
override func layoutSubviews() {
super.layoutSubviews()
updateCornerRadius()
}
private func updateCornerRadius() {
layer.cornerRadius = min(bounds.width, bounds.height) / 2
}
Note that the view's bounds are set before the view receives layoutSubviews, and therefore before we update cornerRadius. This is why the bounds.size animation is installed before the cornerRadius animation is requested. Each property's animations are installed inside the property's setter.
When we set cornerRadius, Core Animation asks us for a CAAction to run for it:
override func action(for layer: CALayer, forKey event: String) -> CAAction? {
if event == "cornerRadius" {
if let boundsAnimation = layer.animation(forKey: "bounds.size") as? CABasicAnimation {
let animation = boundsAnimation.copy() as! CABasicAnimation
animation.keyPath = "cornerRadius"
let action = Action()
action.pendingAnimation = animation
action.priorCornerRadius = layer.cornerRadius
return action
}
}
return super.action(for: layer, forKey: event)
}
In the code above, if we're asked for an action for cornerRadius, we look for a CABasicAnimation on bounds.size. If we find one, we copy it, change the key path to cornerRadius, and save it away in a custom CAAction (of class Action, which I will show below). We also save the current value of the cornerRadius property, because Core Animation calls actionForLayer:forKey: before updating the property.
After actionForLayer:forKey: returns, Core Animation updates the cornerRadius property of the layer. Then it runs the action by sending it runActionForKey:object:arguments:. The job of the action is to install whatever animations are appropriate. Here's the custom subclass of CAAction, which I've nested inside CircleView:
private class Action: NSObject, CAAction {
var pendingAnimation: CABasicAnimation?
var priorCornerRadius: CGFloat = 0
public func run(forKey event: String, object anObject: Any, arguments dict: [AnyHashable : Any]?) {
if let layer = anObject as? CALayer, let pendingAnimation = pendingAnimation {
if pendingAnimation.isAdditive {
pendingAnimation.fromValue = priorCornerRadius - layer.cornerRadius
pendingAnimation.toValue = 0
} else {
pendingAnimation.fromValue = priorCornerRadius
pendingAnimation.toValue = layer.cornerRadius
}
layer.add(pendingAnimation, forKey: "cornerRadius")
}
}
}
} // end of CircleView
The runActionForKey:object:arguments: method sets the fromValue and toValue properties of the animation and then adds the animation to the layer. There's a complication: UIKit uses “additive” animations, because they work better if you start another animation on a property while an earlier animation is still running. So our action checks for that.
If the animation is additive, it sets fromValue to the difference between the old and new corner radii, and sets toValue to zero. Since the layer's cornerRadius property has already been updated by the time the animation is running, adding that fromValue at the start of the animation makes it look like the old corner radius, and adding the toValue of zero at the end of the animation makes it look like the new corner radius.
If the animation is not additive (which doesn't happen if UIKit created the animation, as far as I know), then it just sets the fromValue and toValue in the obvious way.
Here's the whole file for your convenience:
import UIKit
class CircleView: UIView {
override func layoutSubviews() {
super.layoutSubviews()
updateCornerRadius()
}
private func updateCornerRadius() {
layer.cornerRadius = min(bounds.width, bounds.height) / 2
}
override func action(for layer: CALayer, forKey event: String) -> CAAction? {
if event == "cornerRadius" {
if let boundsAnimation = layer.animation(forKey: "bounds.size") as? CABasicAnimation {
let animation = boundsAnimation.copy() as! CABasicAnimation
animation.keyPath = "cornerRadius"
let action = Action()
action.pendingAnimation = animation
action.priorCornerRadius = layer.cornerRadius
return action
}
}
return super.action(for: layer, forKey: event)
}
private class Action: NSObject, CAAction {
var pendingAnimation: CABasicAnimation?
var priorCornerRadius: CGFloat = 0
public func run(forKey event: String, object anObject: Any, arguments dict: [AnyHashable : Any]?) {
if let layer = anObject as? CALayer, let pendingAnimation = pendingAnimation {
if pendingAnimation.isAdditive {
pendingAnimation.fromValue = priorCornerRadius - layer.cornerRadius
pendingAnimation.toValue = 0
} else {
pendingAnimation.fromValue = priorCornerRadius
pendingAnimation.toValue = layer.cornerRadius
}
layer.add(pendingAnimation, forKey: "cornerRadius")
}
}
}
} // end of CircleView
My answer was inspired by this answer by Simon.
This answer builds upon the earlier answer by rob mayoff. Basically, I implemented it for our project and it worked just fine on the iPhone (iOS 9 and 10), but the issue remained on iPad (iOS 9 or 10).
Debugging, I found that the if statement:
if let boundsAnimation = layer.animation(forKey: "bounds.size") as? CABasicAnimation {
always failed on iPad. It looks like the animations are built in a different sequence on iPad than iPhone. Looking back at the original answer by Simon, it seems that sequencing has changed before. So I combined both answers giving me something like this:
override func action(for layer: CALayer, forKey event: String) -> CAAction? {
let buildAction: (CABasicAnimation) -> Action = { boundsAnimation in
let animation = boundsAnimation.copy() as! CABasicAnimation
animation.keyPath = "cornerRadius"
let action = Action()
action.pendingAnimation = animation
action.priorCornerRadius = layer.cornerRadius
return action
}
if event == "cornerRadius" {
if let boundsAnimation = layer.animation(forKey: "bounds.size") as? CABasicAnimation {
return buildAction(boundsAnimation)
} else if let boundsAnimation = self.action(for: layer, forKey: "bounds") as? CABasicAnimation {
return buildAction(boundsAnimation)
}
}
return super.action(for: layer, forKey: event)
}
By combining both answers, it seems to work properly on both iPhone and iPad under iOS 9 and 10. I haven't really tested further, and don't know enough about CoreAnimation to fully understand this change.
In iOS 10 you don't need to create a CAAction, it works just creating a CABasicAnimation and provide this in your action(for layer:, for key:) -> CAAction? function (See Swift example):
private var currentBoundsAnimation: CABasicAnimation? {
return layer.animation(forKey: "bounds.size") as? CABasicAnimation ?? layer.animation(forKey: "bounds") as? CABasicAnimation
}
override public var bounds: CGRect {
didSet {
layer.cornerRadius = min(bounds.width, bounds.height) / 2
}
}
override public func action(for layer: CALayer, forKey event: String) -> CAAction? {
if(event == "cornerRadius"), let boundsAnimation = currentBoundsAnimation {
let animation = CABasicAnimation(keyPath: "cornerRadius")
animation.duration = boundsAnimation.duration
animation.timingFunction = boundsAnimation.timingFunction
return animation
}
return super.action(for: layer, forKey: event)
}
Instead of overriding the bounds property you can also override the layoutSubviews:
override func layoutSubviews() {
super.layoutSubviews()
layer.cornerRadius = min(bounds.width, bounds.height) / 2
}
This works magically because the CABasicAnimation infers the missing from and to values from the model and presentation layers. To set the timing correctly you need the private currentBoundsAnimation property to get the current animations ("bounds" for iPad and "bounds.size" for iPhone) which where added on device rotation.
These translation answers usually go Objective-c ==> Swift, but in case there are any more stubborn Objective-c authors left, here's #Rob's answer translated...
// see https://stackoverflow.com/a/35714554/294949
#import "RoundView.h"
#interface Action : NSObject<CAAction>
#property(strong,nonatomic) CABasicAnimation *pendingAnimation;
#property(assign,nonatomic) CGFloat priorCornerRadius;
#end
#implementation Action
- (void)runActionForKey:(NSString *)event object:(id)anObject
arguments:(nullable NSDictionary *)dict {
if ([anObject isKindOfClass:[CALayer self]]) {
CALayer *layer = (CALayer *)anObject;
if (self.pendingAnimation.isAdditive) {
self.pendingAnimation.fromValue = #(self.priorCornerRadius - layer.cornerRadius);
self.pendingAnimation.toValue = #(0);
} else {
self.pendingAnimation.fromValue = #(self.priorCornerRadius);
self.pendingAnimation.toValue = #(layer.cornerRadius);
}
[layer addAnimation:self.pendingAnimation forKey:#"cornerRadius"];
}
}
#end
#interface RoundView ()
#property(weak,nonatomic) UIImageView *imageView;
#end
#implementation RoundView
- (void)layoutSubviews {
[super layoutSubviews];
[self updateCornerRadius];
}
- (void)updateCornerRadius {
self.layer.cornerRadius = MIN(self.bounds.size.width, self.bounds.size.height)/2.0;
}
- (id<CAAction>)actionForLayer:(CALayer *)layer forKey:(NSString *)event {
if ([event isEqualToString:#"cornerRadius"]) {
CABasicAnimation *boundsAnimation = (CABasicAnimation *)[self.layer animationForKey:#"bounds.size"];
CABasicAnimation *animation = [boundsAnimation copy];
animation.keyPath = #"cornerRadius";
Action *action = [[Action alloc] init];
action.pendingAnimation = animation;
action.priorCornerRadius = layer.cornerRadius;
return action;
}
return [super actionForLayer:layer forKey:event];;
}
#end
I would suggest not using a corner radius, but instead using a CAShapeLayer as a mask for your view's content layer.
You'd install a filled 360° arc CGPath as the shape of the shape layer and set it as the mask of your layer's view.
You could then either animate a new scale transform for the mask layer, or animate a change to the radius of the path. Both methods should stay round, although the scale transform might not give you a clean shape at smaller pixel sizes.
The timing would be the tricky part (getting the animation of the mask layer to happen in lockstep with the bounds animation.)

Remove CALayers from Parent UIView

There are several questions like this floating around, but no answer that works.
I'm adding new CALayers to a UIView like so:
func placeNewPicture() {
let newPic = CALayer()
newPic.contents = self.pictureDragging.contents
newPic.frame = CGRect(x: pictureScreenFrame.origin.x - pictureScreenFrame.width/2, y: pictureScreenFrame.origin.y - pictureScreenFrame.height/2, width: pictureScreenFrame.width, height: pictureScreenFrame.height)
self.drawingView.layer.addSublayer(newPic)
}
and trying to remove them with:
func deleteDrawing() {
for layer in self.drawingView.layer.sublayers {
layer.removeFromSuperlayer()
}
}
This successfully removes the images, but the app crashes the next time the screen is touched, with a call to main but nothing printed in the debugger. There are several situations like this out there, where apps will crash a short time after removing sublayers.
What is the correct way to remove CALayers from their parent View?
I think the error is you delete all sublayers,not the ones you added.
keep a property to save the sublayers you added
var layerArray = NSMutableArray()
Then try
func placeNewPicture() {
let newPic = CALayer()
newPic.contents = self.pictureDragging.contents
newPic.frame = CGRect(x: pictureScreenFrame.origin.x - pictureScreenFrame.width/2, y: pictureScreenFrame.origin.y - pictureScreenFrame.height/2, width: pictureScreenFrame.width, height: pictureScreenFrame.height)
layerArray.addObject(newPic)
self.drawingView.layer.addSublayer(newPic)
}
func deleteDrawing() {
for layer in self.drawingView.layer.sublayers {
if(layerArray.containsObject(layer)){
layer.removeFromSuperlayer()
layerArray.removeObject(layer)
}
}
}
Update with Leo Dabus suggest,you can also just set a name of layer.
newPic.name = "1234"
Then check
func deleteDrawing() {
for layer in self.drawingView.layer.sublayers {
if(layer.name == "1234"){
layerArray.removeObject(layer)
}
}
}

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