CGImageSourceRef imageSource = CGImageSourceCreateWithURL返回NULL

Question

我想獲取圖像的大小而不加載它，所以我正在使用以下代碼

-(float)gettingimagedimensions:(NSString*)url{
    NSURL *imageFileURL = [NSURL fileURLWithPath:url];
    //CGImageSourceRef imageSource = CGImageSourceCreateWithURL(imageFileURL, NULL);
    CGImageSourceRef imageSource = CGImageSourceCreateWithURL((__bridge CFURLRef)imageFileURL, NULL);
    if (imageSource == NULL) {
        // Error loading image

        return 0;
    }

    CGFloat width = 0.0f, height = 0.0f;
    CFDictionaryRef imageProperties = CGImageSourceCopyPropertiesAtIndex(imageSource, 0, NULL);
    if (imageProperties != NULL) {
        CFNumberRef widthNum  = CFDictionaryGetValue(imageProperties, kCGImagePropertyPixelWidth);
        if (widthNum != NULL) {
            CFNumberGetValue(widthNum, kCFNumberFloatType, &width);
        }

        CFNumberRef heightNum = CFDictionaryGetValue(imageProperties, kCGImagePropertyPixelHeight);
        if (heightNum != NULL) {
            CFNumberGetValue(heightNum, kCFNumberFloatType, &height);
        }

        CFRelease(imageProperties);
    }

    NSLog(@"Image dimensions: %.0f x %.0f px", width, height);

    return height;
}

問題是imageSource始終為NULL任何人有任何想法嗎，為什么它不起作用！

請注意，URL是指向JPG或PNG圖片的有效鏈接

Answer 1

您是否啟用了ARC？ 我沒有，我的工作代碼如下：

NSURL * imageFileURL = [NSURL fileURLWithPath:fp];
CGImageSourceRef imageSource = CGImageSourceCreateWithURL((CFURLRef)imageFileURL, NULL);

注意缺少__bridge 。 完成后，我在imageSource上調用CFRelease 。