iOS---如何获取手机的本地照片和相册

__weak ViewController *weakSelf = self;
dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
ALAssetsLibraryGroupsEnumerationResultsBlock listGroupBlock = ^(ALAssetsGroup *group, BOOL *stop) {
if (group != nil) {
[weakSelf.groupArrays addObject:group];
} else {
[weakSelf.groupArrays enumerateObjectsUsingBlock:^(id obj, NSUInteger idx, BOOL *stop) {
[obj enumerateAssetsUsingBlock:^(ALAsset *result, NSUInteger index, BOOL  *stop) {
if ([result thumbnail] != nil) {
// 照片
if ([[result valueForProperty:ALAssetPropertyType] isEqualToString:ALAssetTypePhoto]){

//                                NSDate *date= [result valueForProperty:ALAssetPropertyDate];
//                                UIImage *image = [UIImage imageWithCGImage:[result thumbnail]];
//                                NSString *fileName = [[result defaultRepresentation] filename];
//                                NSURL *url = [[result defaultRepresentation] url];
//                                int64_t fileSize = [[result defaultRepresentation] size];
//
//                                NSLog(@"date = %@",date);
//                                NSLog(@"fileName = %@",fileName);
//                                NSLog(@"url = %@",url);
//                                NSLog(@"fileSize = %lld",fileSize);
//
//                                // UI的更新记得放在主线程,要不然等子线程排队过来都不知道什么年代了,会很慢的
//                                dispatch_async(dispatch_get_main_queue(), ^{
//                                    self.litimgView.image = image;
//                                });
NSLog(@"读取到照片了");
}
// 视频
else if ([[result valueForProperty:ALAssetPropertyType] isEqualToString:ALAssetTypeVideo] ){

NSURL *url = [[result defaultRepresentation] url];
UIImage *image = [UIImage imageWithCGImage:[result thumbnail]];                                NSLog(@"%@",url);
dispatch_async(dispatch_get_main_queue(), ^{
self.litimgView.image = image;
});
// 和图片方法类似
}
}
}];
}];

}
};

ALAssetsLibraryAccessFailureBlock failureBlock = ^(NSError *error)
{

NSString *errorMessage = nil;

switch ([error code]) {
case ALAssetsLibraryAccessUserDeniedError:
case ALAssetsLibraryAccessGloballyDeniedError:
errorMessage = @"用户拒绝访问相册,请在<隐私>中开启";
break;

default:
errorMessage = @"Reason unknown.";
break;
}

dispatch_async(dispatch_get_main_queue(), ^{
UIAlertView *alertView = [[UIAlertView alloc]initWithTitle:@"错误,无法访问!"
message:errorMessage
delegate:self
cancelButtonTitle:@"确定"
otherButtonTitles:nil, nil];
[alertView show];
});
};

ALAssetsLibrary *assetsLibrary = [[ALAssetsLibrary alloc]  init];
[assetsLibrary enumerateGroupsWithTypes:ALAssetsGroupAll
usingBlock:listGroupBlock failureBlock:failureBlock];
});