What's the meaning of progress keypath in CABasicAnimation?

Question

A code snippet from https://github.com/danielamitay/DACircularProgress/blob/master/DACircularProgress/DACircularProgressView.m

CABasicAnimation *animation = [CABasicAnimation animationWithKeyPath:@"progress"];
animation.duration = duration;
animation.timingFunction = [CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionEaseInEaseOut];
animation.fillMode = kCAFillModeForwards;
animation.fromValue = [NSNumber numberWithFloat:self.progress];
animation.toValue = [NSNumber numberWithFloat:pinnedProgress];
animation.beginTime = CACurrentMediaTime() + initialDelay;
animation.delegate = self;
[self.circularProgressLayer addAnimation:animation forKey:@"progress"];

But I could not find progress in the offical document. Does the keypath need to be animatable property? What does the progress mean?

I think you might have misread the code. The `forKey:@"progress"` is "naming" the animation. — James Webster, Nov 17 '16 at 10:57
I mean the `progress` in `[CABasicAnimation animationWithKeyPath:@"progress"];` — Jichao, Nov 17 '16 at 10:58

score 2 · Accepted Answer · edited May 23 '17 at 10:32

2

From this answer (which is coincidentally animating progress too):

Firstly we need to create a new subclass of CALayer that has an animatable property called 'progress'.

Your snippet does indeed have a property called 'progress'

@property(nonatomic) CGFloat progress;

It appears the animation is animating that property

edited May 23 '17 at 10:32

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answered Nov 17 '16 at 11:02

James Webster

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score 0 · Answer 2 · edited May 23 '17 at 10:32

0

It is because the progress is an animatable property for this specific uiview. We could custom animatable property refer: Create a custom animatable property

edited May 23 '17 at 10:32

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answered Nov 17 '16 at 11:01

Jichao

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What's the meaning of progress keypath in CABasicAnimation?

2 Answers2