animation not works in the non-initial UIViewController - ios

Question

I have a UIView called loadingView shows some UIActivityIndicatorView-like animation. There are two UIViewControllers that all have such UIView.
The initial UIViewController's code:
- (void)viewDidLoad {
self.loadingView = [[LoadingView alloc] initWithFrame:CGRectMake(10, 1, 120, 120)];
[self.view addSubview:self.loadingView];
}
Also it has a button to present the second UIViewController:
- (void)buttonPressed {
SecondViewController *sVC = [[SecondViewController alloc] init];
[self presentViewController:sVC animated:YES completion:nil];
}
The second ViewController's viewDidLoad method code:
- (void)viewDidLoad {
self.loadingView = [[LoadingView alloc] initWithFrame:CGRectMake(10, 1, 120, 120)];
[self.view addSubview:self.loadingView];
}
As you can see, the two UIViewControllers has the same viewDidLoad method code.
The loadingView works well in the initial UIViewController.
But in the second UIViewController, the loadingView only displays the black frame( I set the background colour to black).
Here is my loadingView implement code:
#define NUMBER_OF_DOT 15
#define DURATION 1.5
- (id)initWithFrame:(CGRect)frame {
self = [super initWithFrame:frame];
if (self) {
self.replicatorLayer = [[CAReplicatorLayer alloc] init];
self.replicatorLayer.frame = frame;
self.replicatorLayer.cornerRadius = 10.0;
self.replicatorLayer.backgroundColor = [UIColor colorWithRed:0.0 green:0.0 blue:0.0 alpha:0.86].CGColor;
self.replicatorLayer.position = self.center;
self.replicatorLayer.instanceDelay = DURATION/NUMBER_OF_DOT;
[self.layer addSublayer:self.replicatorLayer];
float size = frame.size.width*14/200;
self.dot = [[CALayer alloc] init];
self.dot.bounds = CGRectMake(0, 0, size, size);
self.dot.position = CGPointMake(frame.size.width/2, frame.size.height/5);
self.dot.backgroundColor = [UIColor colorWithWhite:0.8 alpha:1.0].CGColor;
self.dot.borderColor = [UIColor whiteColor].CGColor;
self.dot.borderWidth = 1.0;
self.dot.cornerRadius = 1.5;
self.dot.transform = CATransform3DMakeScale(0.01, 0.01, 0.01);
[self.replicatorLayer addSublayer:self.dot];
self.replicatorLayer.instanceCount = NUMBER_OF_DOT;
float angle = 2*M_PI/NUMBER_OF_DOT;
self.replicatorLayer.instanceTransform = CATransform3DMakeRotation(angle, 0.0, 0.0, 0.1);
self.shrink = [[CABasicAnimation alloc] init];
self.shrink.keyPath = #"transform.scale";
self.shrink.fromValue = [NSNumber numberWithFloat:1.0];
self.shrink.toValue = [NSNumber numberWithFloat:0.1];
self.shrink.duration = DURATION;
self.shrink.repeatCount = INFINITY;
[self.dot addAnimation:self.shrink forKey:nil];
}
return self;
}

Answer 1

-(void)viewDidAppear:(BOOL)animated
{
self.loadingView = [[LoadingView alloc] initWithFrame:CGRectMake(10, 1, 120, 120)];
[self.view addSubview:self.loadingView];
}
Put this code in viewDidAppear of SecondViewController so it works in present mode as well.