ios - 存储在 'imageCrop' 中的对象的潜在泄漏

Question

这段代码运行良好，但在分析时，它显示出潜在的内存泄漏。似乎 imageCrop 有潜在的内存泄漏。非常感谢您的帮助。

这是我的代码。

-(CATransformLayer *)transformLayerFromImage:(UIImage *)image Frame:(CGRect)frame Duration:(CGFloat)duration AnchorPiont:(CGPoint)anchorPoint StartAngle:(double)start EndAngle:(double)end
{
    CATransformLayer *jointLayer = [CATransformLayer layer];
    jointLayer.anchorPoint = anchorPoint;
    CALayer *imageLayer = [CALayer layer];
    CAGradientLayer *shadowLayer = [CAGradientLayer layer];
    double shadowAniOpacity;

    if (anchorPoint.y == 0.5) {
        CGFloat layerWidth;
        if (anchorPoint.x == 0 ) //from left to right
        {
            layerWidth = image.size.width - frame.origin.x;
            jointLayer.frame = CGRectMake(0, 0, layerWidth, frame.size.height);
            if (frame.origin.x) {
                jointLayer.position = CGPointMake(frame.size.width, frame.size.height/2);
            }
            else {
                jointLayer.position = CGPointMake(0, frame.size.height/2);
            }
        }
        else { //from right to left
            layerWidth = frame.origin.x + frame.size.width;
            jointLayer.frame = CGRectMake(0, 0, layerWidth, frame.size.height);
            jointLayer.position = CGPointMake(layerWidth, frame.size.height/2);
        }

        //map image onto transform layer
        imageLayer.frame = CGRectMake(0, 0, frame.size.width, frame.size.height);
        imageLayer.anchorPoint = anchorPoint;
        imageLayer.position = CGPointMake(layerWidth*anchorPoint.x, frame.size.height/2);
        [jointLayer addSublayer:imageLayer];
        CGImageRef imageCrop = CGImageCreateWithImageInRect(image.CGImage, frame);
        imageLayer.contents = (__bridge id)imageCrop;
        imageLayer.backgroundColor = [UIColor clearColor].CGColor;

        //add shadow
        NSInteger index = frame.origin.x/frame.size.width;
        shadowLayer.frame = imageLayer.bounds;
        shadowLayer.backgroundColor = [UIColor darkGrayColor].CGColor;
        shadowLayer.opacity = 0.0;
        shadowLayer.colors = [NSArray arrayWithObjects:(id)[UIColor blackColor].CGColor, (id)[UIColor clearColor].CGColor, nil];
        if (index%2) {
            shadowLayer.startPoint = CGPointMake(0, 0.5);
            shadowLayer.endPoint = CGPointMake(1, 0.5);
            shadowAniOpacity = (anchorPoint.x)?0.24:0.32;
        }
        else {
            shadowLayer.startPoint = CGPointMake(1, 0.5);
            shadowLayer.endPoint = CGPointMake(0, 0.5);
            shadowAniOpacity = (anchorPoint.x)?0.32:0.24;
        }
    }
    else{
        CGFloat layerHeight;
        if (anchorPoint.y == 0 ) //from top
        {
            layerHeight = image.size.height - frame.origin.y;
            jointLayer.frame = CGRectMake(0, 0, frame.size.width, layerHeight);
            if (frame.origin.y) {
                jointLayer.position = CGPointMake(frame.size.width/2, frame.size.height);
            }
            else {
                jointLayer.position = CGPointMake(frame.size.width/2, 0);
            }
        }
        else { //from bottom
            layerHeight = frame.origin.y + frame.size.height;
            jointLayer.frame = CGRectMake(0, 0, frame.size.width, layerHeight);
            jointLayer.position = CGPointMake(frame.size.width/2, layerHeight);
        }

        //map image onto transform layer
        imageLayer.frame = CGRectMake(0, 0, frame.size.width, frame.size.height);
        imageLayer.anchorPoint = anchorPoint;
        imageLayer.position = CGPointMake(frame.size.width/2, layerHeight*anchorPoint.y);
        [jointLayer addSublayer:imageLayer];
        CGImageRef imageCrop = CGImageCreateWithImageInRect(image.CGImage, frame);
        imageLayer.contents = (__bridge id)imageCrop;
        imageLayer.backgroundColor = [UIColor clearColor].CGColor;

        //add shadow
        NSInteger index = frame.origin.y/frame.size.height;
        shadowLayer.frame = imageLayer.bounds;
        shadowLayer.backgroundColor = [UIColor darkGrayColor].CGColor;
        shadowLayer.opacity = 0.0;
        shadowLayer.colors = [NSArray arrayWithObjects:(id)[UIColor blackColor].CGColor, (id)[UIColor clearColor].CGColor, nil];
        if (index%2) {
            shadowLayer.startPoint = CGPointMake(0.5, 0);
            shadowLayer.endPoint = CGPointMake(0.5, 1);
            shadowAniOpacity = (anchorPoint.x)?0.24:0.32;
        }
        else {
            shadowLayer.startPoint = CGPointMake(0.5, 1);
            shadowLayer.endPoint = CGPointMake(0.5, 0);
            shadowAniOpacity = (anchorPoint.x)?0.32:0.24;
        }
    }

    [imageLayer addSublayer:shadowLayer];

    //animate open/close animation
    CABasicAnimation* animation = (anchorPoint.y == 0.5)?[CABasicAnimation animationWithKeyPath:@"transform.rotation.y"]:[CABasicAnimation animationWithKeyPath:@"transform.rotation.x"];
    [animation setDuration:duration];
    [animation setFromValue:[NSNumber numberWithDouble:start]];
    [animation setToValue:[NSNumber numberWithDouble:end]];
    [animation setRemovedOnCompletion:NO];
    [jointLayer addAnimation:animation forKey:@"jointAnimation"];

    //animate shadow opacity
    animation = [CABasicAnimation animationWithKeyPath:@"opacity"];
    [animation setDuration:duration];
    [animation setFromValue:[NSNumber numberWithDouble:(start)?shadowAniOpacity:0]];
    [animation setToValue:[NSNumber numberWithDouble:(start)?0:shadowAniOpacity]];
    [animation setRemovedOnCompletion:NO];
    [shadowLayer addAnimation:animation forKey:nil];

    return jointLayer;
}

Answer 1

无论您使用CGImageCreateWithImageInRect创建什么，都应该被释放，因为这是来自非托管内存区域的函数。

1. 使用CGImageRelease释放对非托管对象的引用:

   CGImageRelease(imageCrop);
   imageCrop = NULL;
   

或

1. 使用 __bridge_transfer 而不是 __bridge 将对象所有权通过 CGImageRef 转移到 ARC。

   imageLayer.contents = (__bridge_transfer id)imageCrop;
   

   在这种情况下，ARC 将有效地为您完成#1。

好的读物:

1. 有一篇关于 Objective-C 桥接的好文章:https://stackoverflow.com/a/17256947/351305
2. 及相关问题:Does ARC work with Core Graphics objects?