iOS遍历相册中的图片

 //获取相册的所有图片
 - (void)reloadImagesFromLibrary
 {
     self.images = [[NSMutableArray alloc] init];
     dispatch_async(dispatch_get_main_queue(), ^{

         @autoreleasepool {
             ALAssetsLibraryAccessFailureBlock failureblock = ^(NSError *myerror){
                 NSLog(@"相册访问失败 =%@", [myerror localizedDescription]);
                 if ([myerror.localizedDescription rangeOfString:@"Global denied access"].location!=NSNotFound) {
                     NSLog(@"无法访问相册.请在'设置->定位服务'设置为打开状态.");
                 }else{
                     NSLog(@"相册访问失败.");
                 }
             };

             ALAssetsGroupEnumerationResultsBlock groupEnumerAtion = ^(ALAsset *result, NSUInteger index, BOOL *stop){
                 if (result!=NULL) {

                     if ([[result valueForProperty:ALAssetPropertyType] isEqualToString:ALAssetTypePhoto]) {

                         NSString *urlstr=[NSString stringWithFormat:@"%@",result.defaultRepresentation.url];//图片的url
                         [self.images addObject:urlstr];
                         //NSLog(@"urlStr is %@",urlstr);
                         //result.defaultRepresentation.fullScreenImage//图片的大图
                         //result.thumbnail                             //图片的缩略图小图
                         NSRange range1=[urlstr rangeOfString:@"id="];
                         NSString *resultName=[urlstr substringFromIndex:range1.location+];
                        resultName=[resultName stringByReplacingOccurrencesOfString:@"&ext=" withString:@"."];//格式demo:123456.png

                     }
                 }
             };

             ALAssetsLibraryGroupsEnumerationResultsBlock libraryGroupsEnumeration = ^(ALAssetsGroup* group, BOOL* stop){

                 if (group == nil)
                 {

                 }

                 if (group!=nil) {
                     NSString *g=[NSString stringWithFormat:@"%@",group];//获取相簿的组
                     NSLog(@"gg:%@",g);//gg:ALAssetsGroup - Name:Camera Roll, Type:Saved Photos, Assets count:71

                     NSString *g1=[g substringFromIndex: ] ;
                     NSArray *arr=[[NSArray alloc] init];
                     arr=[g1 componentsSeparatedByString:@","];
                     NSString *g2=[[arr objectAtIndex:] substringFromIndex:];
                     if ([g2 isEqualToString:@"Camera Roll"]) {
                         g2=@"相机胶卷";
                     }
                     NSString *groupName=g2;//组的name

                     [group enumerateAssetsUsingBlock:groupEnumerAtion];
                 }

             };

             ALAssetsLibrary* library = [[ALAssetsLibrary alloc] init];
             [library enumerateGroupsWithTypes:ALAssetsGroupAll
                                    usingBlock:libraryGroupsEnumeration
                                  failureBlock:failureblock];
         }

     });
 }