How to ask for access to photo library on startup?

Question

I'm building an app that has the user take photos from their library to do things. I'm using X-code, and I had this code under 'didFinishLaunchingWithOptions' but keep getting an 'undeclared identifier' error. What to do?

ALAssetsLibraryGroupsEnumerationResultsBlock assetGroupEnumerator =
^(ALAssetsGroup *assetGroup, BOOL *stop) {
    if (assetGroup != nil) {
        // do somthing
     }
};

ALAssetsLibraryAccessFailureBlock assetFailureBlock = ^(NSError *error) {
    LogError(@"Error enumerating photos: %@",[error description]);

};

NSUInteger groupTypes = ALAssetsGroupAll;

[library enumerateGroupsWithTypes:groupTypes usingBlock:assetGroupEnumerator failureBlock:assetFailureBlock];

Answer 1

Too late an answer but you need to define library

ALAssetsLibrary *library = [[ALAssetsLibrary alloc] init];

or better use a class method if you are going to reuse the library for more queries

+ (ALAssetsLibrary *)defaultAssetsLibrary
{
    static dispatch_once_t pred = 0;
    static ALAssetsLibrary *library = nil;
    dispatch_once(&pred, ^{
        library = [[ALAssetsLibrary alloc] init];
    });
    return library;
}