ios - UIGraphics 内存泄漏

Question

这段代码似乎有内存泄漏，但我找不到它。我究竟做错了什么？具体来说，第 1 行和第 2 行会增加应用程序的内存使用量，只有第一行的内存会在上下文结束时消失。

UIGraphicsBeginImageContext(imageView.bounds.size);
[imageView.layer renderInContext:UIGraphicsGetCurrentContext()];
UIImage *newImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();

编辑 1:完整方法代码如下:

UIImageView *imageView = [[UIImageView alloc] initWithImage:image];
[imageView setFrame:CGRectMake(0, 0, self.view.frame.size.width + 16 - ((int)self.view.frame.size.width % 16), self.view.frame.size.height + 16 - ((int)self.view.frame.size.height % 16))]; // If image width and height is not a multiple of 16, the video becomes distorted when written to a file
imageView.contentMode = UIViewContentModeScaleToFill;

[imageView addSubview:[[UIImageView alloc] initWithImage:[ViewController makeRedCircle]]];

UIGraphicsBeginImageContext(imageView.bounds.size);
[imageView.layer renderInContext:UIGraphicsGetCurrentContext()];
UIImage *newImage = UIGraphicsGetImageFromCurrentImageContext();

UIGraphicsEndImageContext();

Answer 1

您的代码没有任何内在的泄漏:

UIGraphicsBeginImageContext(imageView.bounds.size);
[imageView.layer renderInContext:UIGraphicsGetCurrentContext()];
UIImage *newImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();

也没有任何泄漏的证据。为了测试，我创建了一个应用程序，其唯一代码如下:

@interface ViewController ()
@property (weak, nonatomic) IBOutlet UIImageView* imageView;
@end

@implementation ViewController

- (void)viewDidLoad {
    [super viewDidLoad];
    UIImageView* imageView = self.imageView;
    for (int i = 0; i <= 10; i++) {
        // Here is your code in action!
        UIGraphicsBeginImageContext(imageView.bounds.size);
        [imageView.layer renderInContext:UIGraphicsGetCurrentContext()];
        UIImage *newImage = UIGraphicsGetImageFromCurrentImageContext();
        UIGraphicsEndImageContext();
    }
}

@end

没有泄漏；循环的连续迭代不会增加应用程序的内存。

因此我们可以得出结论，如果您的应用的内存在增长，那是因为您正在做其他事情(例如您稍后对图像所做的事情)。