如何在iPhone中裁剪或獲取較小尺寸的UIImage而不會出現內存泄漏？

Question

我正在使用導航控制器，在其中按如下方式推送tableview控制器：

TableView * Controller = [[TableView alloc] initWithStyle：UITableViewStylePlain]; [self.navigationController pushViewController：Animated：NO]； [控制器發布]；

在此表視圖中，我使用以下兩種方法顯示圖像：

- (UIImage*) getSmallImage:(UIImage*) img
{
    CGSize size = img.size;
    CGFloat ratio = 0;
    if (size.width < size.height) {
        ratio = 36 / size.width;
    } else {
        ratio = 36 / size.height;
    }
    CGRect rect = CGRectMake(0.0, 0.0, ratio * size.width, ratio * size.height);

    UIGraphicsBeginImageContext(rect.size);
    [img drawInRect:rect];

    return UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();
}

- (UIImage*)imageByCropping:(UIImage *)imageToCrop toRect:(CGRect)rect
{

    //create a context to do our clipping in
    UIGraphicsBeginImageContext(rect.size);
    CGContextRef currentContext = UIGraphicsGetCurrentContext();

    //create a rect with the size we want to crop the image to
    //the X and Y here are zero so we start at the beginning of our
    //newly created context

    CGFloat X = (imageToCrop.size.width - rect.size.width)/2;
    CGFloat Y = (imageToCrop.size.height - rect.size.height)/2;


    CGRect clippedRect = CGRectMake(X, Y, rect.size.width, rect.size.height);
    //CGContextClipToRect( currentContext, clippedRect);



    //create a rect equivalent to the full size of the image
    //offset the rect by the X and Y we want to start the crop
    //from in order to cut off anything before them
    CGRect drawRect = CGRectMake(0,
                                 0,
                                 imageToCrop.size.width,
                                 imageToCrop.size.height);

    CGContextTranslateCTM(currentContext, 0.0, drawRect.size.height);
    CGContextScaleCTM(currentContext, 1.0, -1.0);
    //draw the image to our clipped context using our offset rect
    //CGContextDrawImage(currentContext, drawRect, imageToCrop.CGImage);


    CGImageRef tmp = CGImageCreateWithImageInRect(imageToCrop.CGImage, clippedRect);

    //pull the image from our cropped context
    UIImage *cropped = [UIImage imageWithCGImage:tmp];//UIGraphicsGetImageFromCurrentImageContext();
    CGImageRelease(tmp);
    //pop the context to get back to the default
    UIGraphicsEndImageContext();

    //Note: this is autoreleased*/
    return cropped;
}

但是當我彈出Controller時，正在使用的內存不會釋放。 上面用於創建和裁剪圖像的代碼中是否存在任何泄漏。

也有任何有效的方法來處理iPhone中的圖像。 在解決內存問題時，我有很多圖像並且面臨很多挑戰。

提前發送。

Answer 1

我不知道這一點，但這可能是一個問題：

return UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();

第二行永遠不會運行，因為第一行返回