iphone - 如何获取 iPhone 图库中的最新照片？

Question

在我的应用程序中有一个按钮，用户只需单击它就可以直接在屏幕上检索图库中的最新照片。如何获取图库中的最新照片？

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2012/02/17

这样可以得到ALAsset

void (^assetEnumerator)(ALAsset *, NSUInteger, BOOL *) = ^(ALAsset *result, NSUInteger index, BOOL *stop)
    {
        if(result != nil)
        {

            [self.assets addObject:result];

        }
    };

    void (^assetGroupEnumerator)(ALAssetsGroup *, BOOL *) = ^(ALAssetsGroup *group, BOOL *stop)
    {
        if(group != nil)
        {
            [group setAssetsFilter:[ALAssetsFilter allPhotos]];
            [group enumerateAssetsUsingBlock:assetEnumerator];
        }else{
            self.image = [self getLastImage];

        }

    };
    ALAssetsLibraryAccessFailureBlock failureblock = ^(NSError *myerror){
        NSLog(@"error occour =%@", [myerror localizedDescription]);
    };


    assets = [[NSMutableArray alloc] init];
    ALAssetsLibrary *assetsLibrary = [[ALAssetsLibrary alloc] init];
    [assetsLibrary enumerateGroupsWithTypes:ALAssetsGroupAll usingBlock:assetGroupEnumerator failureBlock:failureblock];
    [assetsLibrary release];

我用这个来获取文件日期

    assetURLArray = [[NSMutableArray alloc] init];
    for (ALAsset *asset in self.assets) {
        NSDate * date = [asset valueForProperty:ALAssetPropertyDate];

然后我发现assetURLArray里面总是最靠前的一张，所以最后就这样拿到了最新的一张

if (self.assets && [self.assets count]) {
        ALAsset *asset = [self.assets objectAtIndex:([self.assets count] - 1)];
        CGImageRef ref = [[asset defaultRepresentation]fullResolutionImage];

我不知道这是否总是有效...希望任何人都可以证明我。

我正在寻找一种同步线程的方法...

Answer 1

按照ALAssetsGroup的方法就可以了

(void)enumerateAssetsWithOptions:(NSEnumerationOptions)options usingBlock:(ALAssetsGroupEnumerationResultsBlock)enumerationBlock;**

    applying **NSEnumerationReverse** option

    void (^assetEnumerator)(ALAsset *, NSUInteger, BOOL *) = ^(ALAsset *result, NSUInteger index, BOOL *stop)
        {
            if(result != nil)
            {

                [self.assets addObject:result];

            }
        };

        void (^assetGroupEnumerator)(ALAssetsGroup *, BOOL *) = ^(ALAssetsGroup *group, BOOL *stop)
        {
            if(group != nil)
            {
                [group setAssetsFilter:[ALAssetsFilter allPhotos]];
                [group enumerateAssetsWithOptions:NSEnumerationReverse usingBlock:assetEnumerator];
            }

        };
        ALAssetsLibraryAccessFailureBlock failureblock = ^(NSError *myerror){
            NSLog(@"error occour =%@", [myerror localizedDescription]);
        };


        assets = [[NSMutableArray alloc] init];
        ALAssetsLibrary *assetsLibrary = [[ALAssetsLibrary alloc] init];
        [assetsLibrary enumerateGroupsWithTypes:ALAssetsGroupSavedPhotos usingBlock:assetGroupEnumerator failureBlock:failureblock];
        [assetsLibrary release];


    **Your self.assets array will have latest images**