CAKeyframeAnimation 关键帧动画

1.添加position动画

    CAKeyframeAnimation * _animation=[CAKeyframeAnimation animation];
    _animation.keyPath=@"position";
    NSMutableArray * _frames=[NSMutableArray new];
    for(int i=0;i<10*_totalFilterTime;i++){
        float _leftBorder=_leftButton.frame.origin.x+i/(_totalFilterTime*10.0)*(_upperView.frame.size.width-kFlagViewWidth);
        NSValue * _frameValue=[NSValue valueWithCGPoint:CGPointMake(_leftBorder+_size.width/2, _flagView.frame.origin.y+_flagView.frame.size.height/2)];
        [_frames addObject:_frameValue];
    }
    _animation.values=_frames;
    _animation.duration=_totalFilterTime;
    _animation.timingFunction=[CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionLinear];
    [_flagView.layer addAnimation:_animation forKey:nil];

2.使用CAKeyframeAnimation显示GIF

【1】.首先解析出GIF分帧数据

-(float)getFrameDurationAtIndex:(NSUInteger)index source:(CGImageSourceRef)source
{
    float _frameDuration = 0.1f;
    CFDictionaryRef _properties = CGImageSourceCopyPropertiesAtIndex(source, index, nil);
    NSDictionary * _dict = (__bridge NSDictionary *)_properties;
    NSDictionary * _gifDict = [_dict objectForKey:(NSString *)kCGImagePropertyGIFDictionary];

    NSNumber * _delayUnclamped = _gifDict[(NSString *)kCGImagePropertyGIFUnclampedDelayTime];//  获取该帧图片播放时长
    if (_delayUnclamped) {
        _frameDuration = [_delayUnclamped floatValue];
    }
    else {
        NSNumber * _delayTime = [_gifDict objectForKey:(NSString *)kCGImagePropertyGIFDelayTime];
        if (_delayTime) {
            _frameDuration = [_delayTime floatValue];
        }
    }

    if (_frameDuration < 0.011f) {
        _frameDuration = 0.100f;
    }
    CFRelease(_properties);
    return _frameDuration;
}

【2】.根据每帧的图片和时长设置CAKeyframeAnimation

    CAKeyframeAnimation * _animation=[CAKeyframeAnimation animationWithKeyPath:@"contents"];
    NSMutableArray * _timeArray=[NSMutableArray new];
    NSMutableArray * _imageArray=[NSMutableArray new];

    float _currentTime=0;
    for(NSInteger i=_index;i<MIN(_index+_lenght, _allZhens.count);i++){
        NSDictionary * _dict=[_allZhens objectForKey:[NSNumber numberWithInteger:i]];
        UIImage * _image=[_dict objectForKey:kPerZhenImage];
        [_imageArray addObject:(__bridge UIImage *)_image.CGImage];
        [_timeArray addObject:[NSNumber numberWithFloat:_currentTime/_totalFilterTime]];
        _currentTime+=[[_dict objectForKey:kPerZhenDuration] floatValue];
    }
    _animation.keyTimes=_timeArray;
    _animation.values=_imageArray;
    _animation.timingFunction=[CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionLinear];
    _animation.duration=_totalFilterTime;
    [_gifImageView.layer addAnimation:_animation forKey:@"gifAnimation"];