获取照片库中 某张图片的详细信息（拍照时间，地点）

-(void)imagePickerController:(UIImagePickerController *)picker didFinishPickingMediaWithInfo:(NSDictionary *)info

{

    //获取图片的NSURL来源于AssetsLibrary.framework  #import <AssetsLibrary/AssetsLibrary.h>

    NSURL *url = [infoobjectForKey:UIImagePickerControllerReferenceURL];

    

    //ALAssetsLibrary 获取图片和视频

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

    

    //根据url获取指定的图片 如果获取到了资源执行resultBlock，否则执行failureBlock

    //ALAsset实例代表一个图片或者视频

    [library assetForURL:url resultBlock:^(ALAsset *asset){

        //defaultRepresentation 获取资源文件的默认属性

        //metadata获取数据的数据，就是在默认属性中的数据，称之为元数据

        NSDictionary *imageData = [[NSMutableDictionary alloc]initWithDictionary:asset.defaultRepresentation.metadata];

        //kCGImagePropertyGPSDictionary 关于GPS的字典数据  来源于ImageIO.framework  #import <ImageIO/ImageIO.h>

        NSDictionary *gpsData = [imageData objectForKey:(NSString *)kCGImagePropertyGPSDictionary];

       //打印纬度

        NSLog(@"%@",[gpsData objectForKey:@"Altitude"]);

    }failureBlock:^(NSError *error){

        NSLog(@"error:%@",error);

    }];

}