导航后视图停止动画

Question

I create my custom loading indicator. So, I update my view like this

@property (nonatomic, readonly) CAShapeLayer *progressLayer;
@property (nonatomic, readwrite) BOOL isAnimating;

- (void)layoutSubviews {
    [super layoutSubviews];

    self.progressLayer.frame = CGRectMake(0, 0, CGRectGetWidth(self.bounds), CGRectGetHeight(self.bounds));
    [self updatePath];
}

- (void)updatePath {
    CGPoint center = CGPointMake(CGRectGetMidX(self.bounds), CGRectGetMidY(self.bounds));
    CGFloat radius = MIN(CGRectGetWidth(self.bounds) / 2, CGRectGetHeight(self.bounds) / 2) - self.progressLayer.lineWidth / 2;
    CGFloat startAngle = 3 * M_PI_2;
    CGFloat endAngle = self.endAngle;
    UIBezierPath *path = [UIBezierPath bezierPathWithArcCenter:center radius:radius   startAngle:startAngle endAngle:endAngle clockwise:YES];
    self.progressLayer.path = path.CGPath;
}

Animation starts here

- (void)startAnimating {
    if (self.isAnimating)
    return;

    CABasicAnimation *animation = [CABasicAnimation animation];
    animation.keyPath = @"transform.rotation";
    animation.duration = 1.0f;
    animation.fromValue = @(0.0f);
    animation.toValue = @(2 * M_PI);
    animation.repeatCount = INFINITY;

    [self.progressLayer addAnimation:animation forKey:kLLARingSpinnerAnimationKey];
    self.isAnimating = true;
}

- (void)stopAnimating {
    if (!self.isAnimating)
        return;

    [self.progressLayer removeAnimationForKey:kLLARingSpinnerAnimationKey];
    self.isAnimating = false;
}

- (CAShapeLayer *)progressLayer {
    if (!_progressLayer) {
        _progressLayer = [CAShapeLayer layer];
        _progressLayer.strokeColor = self.tintColor.CGColor;
        _progressLayer.fillColor = nil;
        _progressLayer.lineWidth = 1.5f;
    }
    return _progressLayer;
}

I have a tab bar app, so the problem is when animation start, I click to another tab and then return to first view, my custom indicator doesn't animate. Also this bug(feature) appear in collection view cells if I add my indicator to cells. I add my indicator by calling simple method addSubview:

[view addSubview:indicator];
[indicator startAnimating];

How can I prevent stop animating after navigation? Thanks in advance.

Answer 1

Here you go,

//I have used a BOOL viewChange to check if spinner was running or not while user tapped to different view in tabBar.

- (void)viewWillAppear:(BOOL)animated{  //On initial run the viewChange will be false and the condition in if won't run but as spinnerView start animating u could change the viewChange flag to true.

  //So when user will be back from second view then this flag would be true and it will start animating.

  //As your work is complete then just stop animating and remove from view.

  if(viewChange){
     [spinnerView stopAnimating];
     [spinnerView removeFromSuperview];
     spinnerView = nil;
     spinnerView = [[LLARingSpinnerView alloc] initWithFrame:CGRectMake(self.view.frame.size.width/2, self.view.frame.size.height/2, 40, 40)];

     [self.view addSubview:spinnerView];
     [spinnerView startAnimating];
  }
}

- (void)viewWillDisappear:(BOOL)animated{

//This is called when user move from current view to another and at that point we user won't be seeing the spinnerView so remove it and release it only if it's animating.

  if(spinnerView.isAnimating){
    viewChange = YES;
    [spinnerView stopAnimating];
    [spinnerView removeFromSuperview];
    spinnerView = nil;
  }
  else{
    viewChange = NO;
 }
}

- (IBAction)stopBtn:(id)sender{        //Spinner is stop animating with tap on button and is removed from the view.
  if(spinnerView.isAnimating){
      [spinnerView stopAnimating];
      [spinnerView removeFromSuperview];
      spinnerView = nil;               //release the obj of spinnerView.
  }
}

- (IBAction)btnTap:(id)sender{         //Spinner is start animating with tap on button
  if(!spinnerView)
    spinnerView = [[LLARingSpinnerView alloc] initWithFrame:CGRectMake(self.view.frame.size.width/2, self.view.frame.size.height/2, 40, 40)];
  spinnerView.lineWidth = 1.5f;
  spinnerView.tintColor = [UIColor redColor];
  [self.view addSubview:spinnerView];

  [spinnerView startAnimating];
}

Hope this helps out and if any doubt do let me know. Also if possible u should avoid user to move to another view when spinnerView is running as it indicates that some sort of service or update is running and at that point user should move to another view till it's finish.