问题
This seems to be a very weird issue. I have a small image view in storyBoard and have added tap gesture to it. On the action of gesture I am trying to add a different image view.
Objective C code-
-(void)tapImage{
bigImageView = [[UIImageView alloc]init];
[bigImageView setImage:[UIImage imageNamed:@"main.png"]];
[bigImageView setFrame:CGRectMake(0, 0, 50, 50)];
[self.view addSubview:bigImageView];
[UIView animateWithDuration:2.0 delay:2.0 options:UIViewAnimationOptionCurveEaseInOut
animations:^(void) {
[bigImageView setFrame:CGRectMake(0, 0, self.view.frame.size.width, self.view.frame.size.height)]; //Leave it empty
}
completion:^(BOOL finished){
// Your code goes here
}];
}
Works totally fine.
Swift Code -
func imageTapped()
{
println("Tapped on Image")
bigImageView = UIImageView(frame: CGRectMake(0, 0, 50, 50))
bigImageView.image = UIImage(named: "main")
self.view.addSubview(self.bigImageView)
UIView.animateWithDuration(2.0, delay: 2.0, options:UIViewAnimationOptions.CurveEaseInOut, animations: { () -> Void in
dispatch_async(dispatch_get_main_queue()) {
self.bigImageView = UIImageView(frame: CGRectMake(0, 0, 320, 500))
}
}) { (completed:Bool) -> Void in
}
}
Does not work. I don't know where am I wrong. :(
UPDATE -
First I change the frame with "bigimageview.frame" so now it was displaying image view in gesture tap. But without animation.
So I removed dipatch on main thread and it was animating.
UIView.animateWithDuration(0.4, delay: 0.0, options:UIViewAnimationOptions.CurveEaseInOut, animations: { () -> Void in
// dispatch_async(dispatch_get_main_queue()) {
self.bigImageView.frame = CGRectMake(0, 0, 320, 500)
// }
}) { (completed:Bool) -> Void in
} }
But Still question remains why it happened. Are we not suppose to put UI changes on main thread inside closure/block? Some one please explain.
回答1:
Replace this code
UIView.animateWithDuration(2.0, delay: 1.0, options:UIViewAnimationOptions.CurveEaseInOut, animations: { () -> Void in
dispatch_async(dispatch_get_main_queue()) {
self.bigImageView = UIImageView(frame: CGRectMake(0, 0, 320, 500))
}
}) { (completed:Bool) -> Void in
} }
with
UIView.animateWithDuration(2.0, delay: 1.0, options:UIViewAnimationOptions.CurveEaseInOut, animations: { () -> Void in
dispatch_async(dispatch_get_main_queue()) {
bigImageView.frame = CGRectMake(0, 0, 320, 500)
}
}) { (completed:Bool) -> Void in
} }
回答2:
viewDidLoad() is not the ideal place where you should animate views. viewDidAppear() method may works.
回答3:
There is nothing to be gained by trying to use dispatch_async(). The way animations work you simply set the attributes in the specified animation block; the values are, in fact, set immediately and iOS uses the GPU where possible to animate the transition. If you run the block of code on a different thread it will be outside the scope of the animation and hence simply have an immediate effect.
回答4:
AnimationWithDuration block takes all of its data(duration, options etc). Your dispatching block simply iterates separately. Thats why its not animating. Reason is simple: everything inside dispatch block iterates separately of other code because of stack system. Frame stopped, dispatch putted to stack, executed, and when it gets back to animation: hop, its already has final value and no animations needed.
回答5:
Might be your delay and animation time is same so try this
func imageTapped() {
print("Tapped on Image")
bigImageView = UIImageView(frame: CGRect(x: 0, y: 0, width: 50, height: 50))
bigImageView.image = UIImage(named: "main")
self.view.addSubview(self.bigImageView)
UIView.animate(withDuration: 2.0, delay: 1.0, options:UIView.AnimationOptions.curveEaseInOut, animations: { () -> Void in
DispatchQueue.main.async {
self.bigImageView = UIImageView(frame: CGRect(x: 0, y: 0, width: 320, height: 500))
}
}) { (completed:Bool) -> Void in
}
}
来源：https://stackoverflow.com/questions/31604300/uiview-animatewithduration-does-not-works-in-swift