在使用核心动画代理的时候出现内存泄露，主要是因为delegate 是strong修饰的导致循环引用, 释放不了就内存泄漏了，下图所示：

image.png

通过自定义代理方法可以解决内存泄露问题。以下是自定义代理方法的代码：

#import <UIKit/UIKit.h>

@protocol KKAnimationDelegateDelegate <NSObject>

@optional
//动画结束
- (void)finishAnimation;
//动画开始
- (void)startAnimation;
@end

@interface KKAnimationDelegate : NSObject
@property (weak, nonatomic) id<KKAnimationDelegateDelegate> delegate;
@end

#import "KKAnimationDelegate.h"

@implementation KKAnimationDelegate
- (void)animationDidStart:(CAAnimation *)anim {
    if (_delegate && [_delegate respondsToSelector:@selector(startAnimation)]) {
        [_delegate startAnimation];
    }
}

- (void)animationDidStop:(CAAnimation *)anim finished:(BOOL)flag {
    if (_delegate && [_delegate respondsToSelector:@selector(finishAnimation)]) {
        [_delegate finishAnimation];
    }
}


- (void)dealloc {
    NSLog(@"Delegate Dealloc");
}
@end

使用自定义代理代码

CABasicAnimation *anim = [CABasicAnimation animationWithKeyPath:@"transform.rotation"];
anim.fillMode = kCAFillModeForwards;
KKAnimationDelegate *animationDelegate = [[KKAnimationDelegate alloc] init];
animationDelegate.delegate = self;
[anim setDelegate:animationDelegate];
[anim setTimingFunction:[CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionEaseInEaseOut]];
    
[_imgView.layer addAnimation:anim forKey:@"rotation"];
//防止CABasicAnimation 按home键切到后台之后，再按home键回来动画就停止了
anim.removedOnCompletion = NO;