照片框架requestImageDataForAsset偶尔会失败 [英] Photos Framework requestImageDataForAsset occasionally fails

问题描述

我正在使用iOS8.1上的照片框架并使用requestImageDataForAsset请求资产的图像数据...大部分时间它都有效，我得到的图像数据和包含您在下面看到的内容的字典。但有时调用完成，但数据为零，字典包含三个通用的查找条目。

I'm using the photos framework on iOS8.1 and requesting the image data for the asset using requestImageDataForAsset... Most of the time it works and I get the image data and a dictionary containing what you see below. But sometimes the call completes, but the data is nil and the dictionary contains three generic looking entries.

调用按顺序执行并在同一个线程上执行。它不是特定于任何特定图像。错误将发生在我过去成功打开的图像上。有没有人遇到过这个？

The calls are performed sequentially and on the same thread. It is not specific to any particular image. The error will happen on images I've successfully opened in the past. Has anyone encountered this?

+ (NSData *)retrieveAssetDataPhotosFramework:(NSURL *)urlMedia resolution:(CGFloat)resolution imageOrientation:(ALAssetOrientation*)imageOrientation {

    __block NSData *iData = nil;

    PHFetchResult *result = [PHAsset fetchAssetsWithALAssetURLs:@[urlMedia] options:nil];
    PHAsset *asset = [result firstObject];

    PHImageManager *imageManager = [PHImageManager defaultManager];
    PHImageRequestOptions *options = [[PHImageRequestOptions alloc]init];
    options.synchronous = YES;
    options.version = PHImageRequestOptionsVersionCurrent;

    @autoreleasepool {
        [imageManager requestImageDataForAsset:asset options:options resultHandler:^(NSData *imageData, NSString *dataUTI, UIImageOrientation orientation, NSDictionary *info) {
            iData = [imageData copy];
            NSLog(@"requestImageDataForAsset returned info(%@)", info);
            *imageOrientation = (ALAssetOrientation)orientation;
        }];
    }

    assert(iData.length != 0);
    return iData;
}

这是我获取图像数据和元数据字典的理想结果：

This is the desired result where I get image data and the dictionary of meta data:

requestImageDataForAsset returned info({
    PHImageFileDataKey = <PLXPCShMemData: 0x1702214a0> bufferLength=1753088 dataLength=1749524;
    PHImageFileOrientationKey = 1;
    PHImageFileSandboxExtensionTokenKey = "6e14948c4d0019fbb4d14cc5e021199f724f0323;00000000;00000000;000000000000001a;com.apple.app-sandbox.read;00000001;01000003;000000000009da80;/private/var/mobile/Media/DCIM/107APPLE/IMG_7258.JPG";
    PHImageFileURLKey = "file:///var/mobile/Media/DCIM/107APPLE/IMG_7258.JPG";
    PHImageFileUTIKey = "public.jpeg";
    PHImageResultDeliveredImageFormatKey = 9999;
    PHImageResultIsDegradedKey = 0;
    PHImageResultIsInCloudKey = 0;
    PHImageResultIsPlaceholderKey = 0;
    PHImageResultWantedImageFormatKey = 9999;
})

这就是我得到的偶尔。图像数据为零。字典包含的不多。

Here's what I get occasionally. image data is nil. Dictionary contains not so much.

requestImageDataForAsset returned info({
    PHImageResultDeliveredImageFormatKey = 9999;
    PHImageResultIsDegradedKey = 0;
    PHImageResultWantedImageFormatKey = 9999;
})

推荐答案

您可能正在遍历数组，并且内存未及时释放，您可以尝试以下代码。确保 theData 标记为 __ block 。

You are likely iterating through an array, and memory is not freed timely, you can try the below code. Make sure theData is marked by __block.

@autoreleasepool {
    [imageManager requestImageDataForAsset:asset options:options resultHandler:^(NSData *imageData, NSString *dataUTI, UIImageOrientation orientation, NSDictionary *info) {
        NSLog(@"requestImageDataForAsset returned info(%@)", info);
        theData = [imageData copy];
    }];
}

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