Setting UIView with animation to default state - ios

Question

I have an animating sine wave in one of my view controllers that appears every time an up swipe gesture is detected and disappears when a down swipe is detected. The sine wave is a UIView and the animation translates the sine wave across the screen. This works fine when I swipe up and down the first time. However, after the first swipe I get all kinds of issues. I noticed that if I reallocate and initialize the sine wave after every swipe down, I can get it to work properly, but I know thats not the correct fix. My assumption is that the frame of the sine wave has to be reset to what it was originally, but my attempt to do so didn't resolve the issue (my attempt is commented out in the code below). Any ideas?
View controller code:
- (void)viewDidLoad
{
[self setUpSine];
[[NSNotificationCenter defaultCenter] addObserver:self selector:#selector(appDidEnterForeground:) name:UIApplicationWillEnterForegroundNotification object:nil];
}
-(void) setUpSine
{
self.sineWave = [[OSDrawWave alloc] initWithFrame:CGRectMake(-1*self.view.bounds.size.width, self.view.bounds.size.height, 2*self.view.bounds.size.width, .3125*(2*self.view.bounds.size.width))];
[self.sineWave setBackgroundColor:[UIColor clearColor]];
[self.view insertSubview:self.sineWave belowSubview:self.panedView];
}
- (IBAction)handleUpSwipe:(UISwipeGestureRecognizer *)recognizer
{
[self.sineWave animateWave];
[self showSine];
[UIView animateWithDuration:.25 delay:0 options:UIViewAnimationOptionCurveLinear animations:^
{
self.sineWave.frame = CGRectOffset(self.sineWave.frame, 0, -246);
}
completion:^(BOOL finished)
{
NSLog(#"sine wave y position AFTER UP swipe %f", self.sineWave.frame.origin.y);
}];
}
- (IBAction)handleDownSwipe:(UISwipeGestureRecognizer *)recognizer
{
[self hideSine];
if(self.panedView.frame.origin.y <0)
{
[UIView animateWithDuration:.25 delay:0 options:UIViewAnimationOptionCurveLinear animations:^
{
self.sineWave.frame = CGRectOffset(self.sineWave.frame, 0, 246);
}
completion:^(BOOL finished)
{
}];
}
}
-(void) showSine
{
[self.sineWave setHidden:NO];
[self.sineWave fadeInAnimation];
}
-(void) hideSine
{
[self.sineWave fadeOutAnimation];
[self.sineWave setHidden:YES];
}
-(void) appDidEnterForeground:(NSNotification *)notification
{
[self.sineWave animateWave];
}
My sine wave is a subclass of UIView. This is the code within the sineWave class
- (void)animateWave {
[self.layer removeAllAnimations];
self.transform=CGAffineTransformIdentity;
[UIView animateWithDuration:3 delay:0.0 options: UIViewAnimationOptionRepeat | UIViewAnimationOptionCurveLinear | UIViewAnimationOptionAllowUserInteraction animations:^{
self.transform = CGAffineTransformMakeTranslation(self.frame.size.width/2,0);
} completion:^(BOOL finished) {
self.transform = CGAffineTransformMakeTranslation(-self.frame.size.width/2, 0);
}];
}
-(void) fadeInAnimation
{
[UIView animateWithDuration:0 animations:^{
self.alpha = 1.0;}];
}
-(void) fadeOutAnimation
{
[UIView animateWithDuration:3 animations:^{
self.alpha = 0.0;}];
}
- (void)drawRect:(CGRect)rect
{
self.yc = 30;//The height of a crest.
float w = 0;//starting x value.
float y = rect.size.height;
float width = rect.size.width;
int cycles = 6;//number of waves
self.x = width/cycles;
CGContextRef context = UIGraphicsGetCurrentContext();
CGMutablePathRef path = CGPathCreateMutable();
CGContextSetLineWidth(context, 2);
while (w <= width) {
CGPathMoveToPoint(path, NULL, w,y/2);
CGPathAddQuadCurveToPoint(path, NULL, w+self.x/4, y/2 - self.yc, w+self.x/2, y/2);
CGPathAddQuadCurveToPoint(path, NULL, w+3*self.x/4, y/2 + self.yc, w+self.x, y/2);
w+=self.x;
}
CGContextAddPath(context, path);
[[UIColor colorWithRed:107/255.0f green:212/255.0f blue:231/255.0f alpha:1.0f]setStroke];
CGContextDrawPath(context, kCGPathStroke);
self.alpha= 0.0;
}

Answer 1

I was able to get this working thanks to a clue from this answer
In the view controller you need to subscribe to UIApplicationWillEnterForegroundNotification to get a notification when you app is returning from the background. I changed the viewDidLoad in the view controller and added a method to handle the notification -
- (void)viewDidLoad
{
[super viewDidLoad];
[self setUpSine];
[self.sineWave animateWave];
[[NSNotificationCenter defaultCenter] addObserver:self selector:#selector(appDidEnterForeground:) name:UIApplicationWillEnterForegroundNotification object:nil];
}
-(void) appDidEnterForeground:(NSNotification *)notification
{
[self.sineWave animateWave];
}
I also removed the call to animateWave from the handleUpSwipe: method
- (IBAction)handleUpSwipe:(UISwipeGestureRecognizer *)recognizer
{
[self showSine];
[UIView animateWithDuration:.25 delay:0 options:UIViewAnimationOptionCurveLinear animations:^
{
self.sineWave.frame = CGRectOffset(self.sineWave.frame, 0, -246);
}
completion:^(BOOL finished)
{
NSLog(#"sine wave y position AFTER UP swipe %f", self.sineWave.frame.origin.y);
}];
}
You also need to make a change to animateWave to clear any previous animation before the animation is (re)started. You don't need anything in the completion block -
- (void)animateWave {
[self.layer removeAllAnimations];
self.transform=CGAffineTransformIdentity;
[UIView animateWithDuration:3 delay:0.0 options: UIViewAnimationOptionRepeat | UIViewAnimationOptionCurveLinear |UIViewAnimationOptionAllowUserInteraction animations:^{
self.transform = CGAffineTransformMakeTranslation(self.frame.size.width/2,0);
} completion:^(BOOL finished) {
}];
}