在arc模式下 CGImage 释放问题

//大图bigImage

//定义myImageRect，截图的区域

if (imagecount >= 3) {

CGRect myImageRect;

if (i.size.width<= i.size.height) {

myImageRect = CGRectMake(0.0, 150.0, i.size.width, i.size.width);

}

else

myImageRect = CGRectMake(0.0, 150.0, i.size.height, i.size.height);

UIImage* bigImage= i;

CGImageRef imageRef = bigImage.CGImage;

CGImageRef subImageRef = CGImageCreateWithImageInRect(imageRef, myImageRect);

CGSize size;

size.width = 80;

size.height = 80;

UIGraphicsBeginImageContext(size);

CGContextRef context = UIGraphicsGetCurrentContext();

CGContextDrawImage(context, myImageRect, subImageRef);

UIImage* smallImage = [UIImage imageWithCGImage:subImageRef];

CGImageRelease(subImageRef);

UIGraphicsEndImageContext();

return smallImage;

}

if (imagecount < 3) {

CGRect myImageRect;

if (i.size.width<= i.size.height) {

myImageRect = CGRectMake(0.0, 150.0, i.size.width, i.size.width*2/3);

}

else

myImageRect = CGRectMake(0.0, 150.0, i.size.height, i.size.height*2/3);

UIImage* bigImage= i;

CGImageRef imageRef = bigImage.CGImage;

CGImageRef subImageRef = CGImageCreateWithImageInRect(imageRef, myImageRect);

CGSize size;

size.width = 120;

size.height = 80;

UIGraphicsBeginImageContext(size);

CGContextRef context = UIGraphicsGetCurrentContext();

CGContextDrawImage(context, myImageRect, subImageRef);

UIImage* smallImage = [UIImage imageWithCGImage:subImageRef];   //注意蓝色的部分

CGImageRelease(subImageRef);

return smallImage;

}

return nil;

}

像这样 裁剪图片 就会有内存泄漏

后来上 stackoverflow 查找 发现这样一段话

ARC does not manage C-types, of which CGImage may be considered. You must release the ref manually when you are finished with CGImageRelease(image);





UIImage* smallImage = [UIImage imageWithCGImage:subImageRef];

CGImageRelease(subImageRef);

UIGraphicsEndImageContext();

也就是 在arc模式下 不是什么东西 都可以释放 例如 C-types的对象 都需要手动来进行释放