Custom Spinner class with rotation animation problem - objective-c

Question

I programmed my own view containing an imageview which should be rotating. Here is my rotation animation:
- (void)startPropeller
{
//_movablePropeller = [[UIImageView alloc] initWithFrame:self.frame];
//_movablePropeller.image = [UIImage imageNamed:#"MovablePropeller"];
//[self addSubview:self.movablePropeller];
self.hidden = NO;
CABasicAnimation *rotation;
rotation = [CABasicAnimation animationWithKeyPath:#"transform.rotation"];
rotation.fromValue = [NSNumber numberWithFloat:0.0f];
rotation.toValue = [NSNumber numberWithFloat:(2 * M_PI)];
rotation.cumulative = true;
rotation.duration = 1.2f; // Speed
rotation.repeatCount = INFINITY; // Repeat forever. Can be a finite number.
[self.movablePropeller.layer removeAllAnimations];
[self.movablePropeller.layer addAnimation:rotation forKey:#"Spin"];
}
And here is how I start it:
self.loadingPropeller = [[FMLoadingPropeller alloc] initWithFrame:self.view.frame andStyle:LoadingPropellerStyleNoBackground];
self.loadingPropeller.center=self.view.center;
[self.view addSubview:self.loadingPropeller];
[self.loadingPropeller startPropeller];
Problem is: Without any further code. The propeller is not rotating. So I was able to solve it by adding this code into my class implementing to rotating propeller spinner:
-(void)viewDidAppear:(BOOL)animated
{
if(!self.loadingPropeller.hidden){
[self.loadingPropeller startPropeller];
}
}
But I don't like that too much. Isn't it possible to add some code within the Propeller class to solve this issue automatically, without having to add also code in every class in the viewDidAppear method?

Answer 1

The code that doesn't work does two essential things: adding the spinner to the view hierarchy and positioning it. My guess is that the failure is due to positioning it before layout has happened. Try this:
// in viewDidLoad of the containing vc...
self.loadingPropeller = [[FMLoadingPropeller alloc] initWithFrame:CGRectZero andStyle:LoadingPropellerStyleNoBackground];
[self.view addSubview:self.loadingPropeller];
// within or after viewDidLayoutSubviews...
// (make sure to call super for any of these hooks)
self.loadingPropeller.frame = self.view.bounds;
self.loadingPropeller.center = self.view.center;
// within or after viewDidAppear (as you have it)...
[self.loadingPropeller startPropeller];