使用PHAsset获取图像或视频文件的大小

分为图片和视频2部分

1. 图片

[[PHImageManager defaultManager] requestImageDataForAsset:asset options:nil resultHandler:^(NSData *imageData, NSString *dataUTI, UIImageOrientation orientation, NSDictionary *info) {
     float imageSize = imageData.length; //convert to MB
     imageSize = imageSize/(1024*1024.0);
     NSLog(@"%f",imageSize);
 }];[[PHImageManager defaul