swift UIGraphicsGetImageFromCurrentImageContext无法释放内存

Question

SWIFT代码

当我们获得UIView的屏幕截图时,我们通常使用以下代码:

UIGraphicsBeginImageContextWithOptions(frame.size, false, scale)
drawViewHierarchyInRect(bounds, afterScreenUpdates: true)
var image:UIImage = UIGraphicsGetImageFromCurrentImageContext()
UIGraphicsEndImageContext()

问题

drawViewHierarchyInRect && UIGraphicsGetImageFromCurrentImageContext将在当前上下文中生成图像,但在调用时不会释放 内存UIGraphicsEndImageContext.

内存使用继续增加,直到应用程序崩溃.

虽然有一个词UIGraphicsEndImageContext会CGContextRelease自动调用",但它不起作用.

我该如何释放内存drawViewHierarchyInRect或UIGraphicsGetImageFromCurrentImageContext使用

要么？

有没有生成截图没有drawViewHierarchyInRect？

已经尝试过了

1自动释放:不起作用

var image:UIImage?
autoreleasepool{
    UIGraphicsBeginImageContextWithOptions(frame.size, false, scale)
    drawViewHierarchyInRect(bounds, afterScreenUpdates: true)
    image = UIGraphicsGetImageFromCurrentImageContext()
    UIGraphicsEndImageContext()
}
image = nil

2 UnsafeMutablePointer:不起作用

var image:UnsafeMutablePointer<UIImage> = UnsafeMutablePointer.alloc(1)

autoreleasepool{
   UIGraphicsBeginImageContextWithOptions(frame.size, false, scale)
   drawViewHierarchyInRect(bounds, afterScreenUpdates: true)
   image.initialize(UIGraphicsGetImageFromCurrentImageContext())
   UIGraphicsEndImageContext()
}
image.destroy()
image.delloc(1)

Answer 1

我通过将图像操作放在另一个队列中解决了这个问题！

private func processImage(image: UIImage, size: CGSize, completion: (image: UIImage) -> Void) {
    dispatch_async(dispatch_get_global_queue(Int(QOS_CLASS_USER_INITIATED.rawValue), 0)) {
        UIGraphicsBeginImageContextWithOptions(size, true, 0)
        image.drawInRect(CGRect(origin: CGPoint.zero, size: size))
        let tempImage = UIGraphicsGetImageFromCurrentImageContext()
        UIGraphicsEndImageContext()

        completion(image: tempImage)
    }
}