When click on the image in my app and the image is at the top, the image will always move down perfectly. But when the image is at the bottom sometimes the image does not move up. Even though it does not move the process is still run and it logs as if it was at the top. I tried everything I know how to do but do you see anything wrong? Thanks!!
- (void )imageTapped:(UITapGestureRecognizer *) gestureRecognizer
{
NSLog(#"imageTapped");
[UIView beginAnimations:#"move" context:nil];
[UIView setAnimationDuration:0.3];
if (self.imgV.frame.origin.y == 20) {
NSLog(#"Top");
upOrDown = #"1";
self.invalidateTheTimer = #"";
timer = [NSTimer scheduledTimerWithTimeInterval:1.0 target:self selector:#selector(updateLabel) userInfo:nil repeats:YES];
self.imgV.frame=CGRectMake(0, self.view.frame.size.height-self.imgV.frame.size.height, self.imgV.frame.size.width, self.imgV.frame.size.height);
self.vBottom.frame=CGRectMake(0, self.imgV.frame.origin.y+self.imgV.frame.size.height, self.vBottom.frame.size.width, self.vBottom.frame.size.height);
} else if (self.imgV.frame.origin.y >= 507) {
NSLog(#"Bottom");
self.imgV.frame=CGRectMake(0, 20, self.imgV.frame.size.width, self.imgV.frame.size.height);
self.vBottom.frame=CGRectMake(0, self.imgV.frame.origin.y+self.imgV.frame.size.height, self.vBottom.frame.size.width, self.vBottom.frame.size.height);
[hour setText:#""];
[minute setText:#""];
[second setText:#""];
[timer invalidate];
self.invalidateTheTimer = #"INVALIDATE";
}
NSLog(#"%f", self.imgV.frame.origin.y);
[UIView commitAnimations];
}
Considering you haven't posted your entire code, it's hard to figure out what's wrong exactly, but looking at the mess you've made, I suggest you take a look into block based animations which should simplify what you're trying to accomplish.
Additionally, if I had to guess, I'd say the issue is in your timer and whatever method it's invoking is probably messing with your animations.
Related
Im using this code to try to detect collisions between two images, one of which is in an animation, but it doesn't work.
[UIView animateWithDuration:5 animations:^{
bird.center = CGPointMake(bird.center.x, 600);
fallTimer = [NSTimer scheduledTimerWithTimeInterval:.001 target:self selector:#selector(check) userInfo:nil repeats:YES];
}];
-(void)check {
if (CGRectIntersectsRect(bird.frame, cat.frame)) {
NSLog(#"YES");
}
}
How can i detect the collision?
You can't use the frame of a view while it's being animated, the returned value will not be accurate. Instead, you should be able to get the presentationLayer from the views layer and check its frame.
I have a button and an image. When the button is pressed and held I want the image to movie across the screen quickly. Right now after I press and hold it just moves after I let go. I need it to start moving after a certain amount of time and stop when I let go.
here is what I have:
- (IBAction)buttonDown:(id)sender
{
[UIView beginAnimations:nil context:nil];
[UIView setAnimationDuration:0.5];
x = x + 100;
}
With below code, you have to push 3 seconds to move _imageView, and then the image begins moving, and when you release the button, the image stops.
- (IBAction)pushToMove:(id)sender {
[self performSelector:#selector(move) withObject:nil afterDelay:3.0];
}
- (void)move
{
_nt = [NSTimer scheduledTimerWithTimeInterval:0.1
target:self
selector:#selector(goRight)
userInfo:nil
repeats:YES];
}
- (void)goRight
{
_imageView.frame = CGRectMake(_imageView.frame.origin.x + 10, _imageView.frame.origin.y,
_imageView.frame.size.width, _imageView.frame.size.height);
}
- (IBAction)stop
{
[NSObject cancelPreviousPerformRequestsWithTarget:self selector:#selector(move) object:nil];
[_nt invalidate];
}
I put this sample project to GitHub. You can download and just run it.
https://github.com/weed/p120804_ImageMoveDuringPushButton
This can be done in interface builder by simply liking to the buttons touch down property instead of touch up inside. In code it looks like this:
[myButton addTarget:self action:#selector(myMethod) forControlEvents:UIControlEventTouchDown];
In addition to this, you'll want to do some state checking on your animation, and use UIViewAnimationOptionBeginFromCurrentState as an option to help it pick up where it left off when the user presses the button again.
I am a beginner when it comes to iOS App development. I want to move a label from left to right until it reaches half the screen width - i.e. the label should move by 240px (the label moves left to right like a marquee).
I have used NSTimer and I want to stop the timer when the label reaches half the view's width.
I have used the following code but it moves the label out of the view:
- (void)viewDidLoad {
[super viewDidLoad];
timer = [[NSTimer scheduledTimerWithTimeInterval:0.09 target:self selector:#selector(time:) userInfo:nil repeats:YES] retain];
}
- (void)time:(NSTimer *)theTimer {
label.center = CGPointMake(label.center.x+3.5, label.center.y);
NSLog(#"point:%#", label);
if (label.center.x < - (label.bounds.size.width/2)) {
label.center = CGPointMake(320+(label.bounds.size.width/2), label.center.y);
}
}
How can I solve this, please?
If you want to stop the repeating timer, you can use
if (/*You label is in position*/)
[myTimer invalidate];
But that's not the normal way to do animation in iOS, try this instead:
CGRect endFrame = /*The frame of your label in end position*/
[UIView animateWithDuration:0.5 animations:^{ myLabel.frame = endFrame;}];
To stop a timer, do [timer invalidate].
You can't "pause" a timer, so once you do this you'll need to call another timer.
correct way to invalidate your timer is
[myTimer invalidate];
myTimer = nil;
I have a button on my UI that I would like to flash (turn on and then off again) every 800ms, once the button has been pressed. I do that with the following code:
- (void)flickEmergencyButton {
// Check whether an emergency is in progress...
if (model.emergencyInProgress) {
// ...and if so, flick the state
self.emergencyButton.selected = !self.emergencyButton.selected;
// Make this method be called again in 800ms
[self performSelector:#selector(flickEmergencyButton) withObject:nil afterDelay:0.8];
} else {
// ...otherwise, turn the button off
self.emergencyButton.selected = NO;
}
}
...which works really well, except: There is a UIScrollView on the UI as well and while the user has his finger down on it and is scrolling around, the button freezes. While I completely understand why that is, I am not sure what to do about it.
The performSelector:withObject:afterDelay message schedules the message to be send on the current thread, which is the main thread, ie. the UI tread and hence does not get to process the message until all other UI activity has come to an end. Correct? But I need to do this on the UI thread as I cannot select/un-select the button on any other thread, right? So what is the solution here?
I would recommend using Core Animation. Try something like this:
-(void) flash{
[UIView beginAnimations:nil context:NULL];
[UIView setAnimationDuration:0.3f];
[UIView setAnimationCurve:UIViewAnimationCurveLinear];
if( emergency ){
// Start flashing
[UIView setAnimationRepeatCount:1000];
[UIView setAnimationRepeatAutoreverses:YES];
[btn setAlpha:0.0f];
}else{
// Stop flashing
[UIView setAnimationBeginsFromCurrentState:YES];
[UIView setAnimationRepeatCount:1];
[btn setAlpha:1.0f];
}
emergency = !emergency;
[UIView commitAnimations];
}
Where btn is declared as
#property(nonatomic, retain) IBOutlet UIButton *btn;
and emergency is a simple BOOL variable.
Call flash to start and to stop the animation.
In this example we animate the alpha attribute for simplicity, but you can do the same with the button backcolor, as Sam said in his answer, or whatever attribute you like.
Hope it helps.
UPDATE:
Regarding making the transition between two images, try calling imageFlash instead of flash:
-(void) imageFlash{
CABasicAnimation *imageAnimation = [CABasicAnimation animationWithKeyPath:#"contents"];
[btn setImage:normalState forState:UIControlStateNormal];
if( emergency ){
imageAnimation.duration = 0.5f;
imageAnimation.repeatCount = 1000;
}else{
imageAnimation.repeatCount = 1;
}
imageAnimation.fromValue = (id)normalState.CGImage;
imageAnimation.toValue = (id)emergencyState.CGImage;
[btn.imageView.layer addAnimation:imageAnimation forKey:#"animateContents"];
[btn setImage:normalState forState:UIControlStateNormal]; // Depending on what image you want after the animation.
emergency = !emergency;
}
Where normalState and emergencyState are the images you want to use:
Declared as:
UIImage *normalState;
UIImage *emergencyState;
Assigning the images:
normalState = [UIImage imageNamed:#"normal.png"];
emergencyState = [UIImage imageNamed:#"alert.png"];
Good luck!
While this feels like a job for CoreAnimation (perhaps animating the backgroundColor of a custom UIControl) you could accomplish this with an NSTimer running in the appropriate run loop mode.
e.x.
NSTimer *timer = [NSTimer timerWithTimeInterval:0.8f target:self selector:#selector(flicker:) userInfo:nil repeats:YES];
[[NSRunLoop currentRunLoop] addTimer:timer forMode:NSRunLoopCommonModes];
and when you want to stop animation:
[timer invalidate], timer = nil;
button.selected = NO;
By adding the timer to all NSRunLoopCommonModes, you not only add it to the default run loop mode but the mode it is in while user interaction is being continuously processed (UITrackingRunLoopMode.)
Apple's docs give a more thorough explanation of run loop modes and run loops in general.
I want to hide an image after one second, as a flip animation ends. Please someone help me.
Assuming that you need to hide after loading from viewDidLoad, Declare following in your viewDidLoad;
[NSTimer scheduledTimerWithTimeInterval:1 target:self selector:#selector(hideYourImage) userInfo:nil repeats:NO];
-(void)hideYourImage
{
[yourImageView setHidden:TRUE];
}
Here you are. Hope it helps.
If you are doing flip animation using UIView animation, then you can specify code for animation completion.
[UIView animateWithDuration:0.2
animations:^{// Put your flip animation}
completion:^(BOOL finished){ [imageView removeFromSuperview]; }];
Else, the timer method will also do.