视频压缩iOS

注意：需要判断之前的文件是否存在 ，如果存在则删除文件 
    [fileManager createDirectoryAtPath:createPath withIntermediateDirectories:YES attributes:nil error:nil];



- (void)convertVideoWithModel{    [self creatSandBoxFilePathIfNoExist];    //保存至沙盒路径    NSString *pathDocuments = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) objectAtIndex:0];    NSString *videoPath = [NSString stringWithFormat:@"%@/Video", pathDocuments];    //转码配置    AVURLAsset *asset = [AVURLAsset URLAssetWithURL:self.videoURL options:nil];        //AVAssetExportPresetMediumQuality可以更改，是枚举类型，官方有提供，更改该值可以改变视频的压缩比例    AVAssetExportSession *exportSession= [[AVAssetExportSession alloc] initWithAsset:asset presetName:AVAssetExportPresetMediumQuality];    exportSession.shouldOptimizeForNetworkUse = YES;    exportSession.outputURL = [NSURL fileURLWithPath:[videoPath stringByAppendingPathComponent:@"fourmVideo.mp4"]];    //AVFileTypeMPEG4 文件输出类型，可以更改，是枚举类型，官方有提供，更改该值也可以改变视频的压缩比例    exportSession.outputFileType = AVFileTypeQuickTimeMovie;    [exportSession exportAsynchronouslyWithCompletionHandler:^{        int exportStatus = exportSession.status;        NSLog(@"%d",exportStatus);        switch (exportStatus)        {            case AVAssetExportSessionStatusFailed:            {                // log error to text view                NSError *exportError = exportSession.error;                NSLog (@"AVAssetExportSessionStatusFailed: %@", exportError);                NSData *videoData = [NSData dataWithContentsOfURL:self.videoURL];                self.loadVideoData(self.videoURL,videoData);                break;            }            case AVAssetExportSessionStatusCompleted:            {                NSLog(@"视频转码成功");                NSData *videoData = [NSData dataWithContentsOfFile:[videoPath stringByAppendingPathComponent:@"fourmVideo.mp4"]];                self.loadVideoData(_videoURL,videoData);            }        }    }];    }- (void)creatSandBoxFilePathIfNoExist{    //沙盒路径    NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);    NSString *documentDirectory = [paths objectAtIndex:0];    NSLog(@"databse--->%@",documentDirectory);        NSFileManager *fileManager = [[NSFileManager alloc] init];    NSString *pathDocuments = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) objectAtIndex:0];    //创建目录    NSString *createPath = [NSString stringWithFormat:@"%@/Video", pathDocuments];    // 判断文件夹是否存在，如果不存在，则创建    if ([[NSFileManager defaultManager] fileExistsAtPath:createPath]) {        NSError *error;        if ([[NSFileManager defaultManager] removeItemAtPath:createPath error:&error] == NO) {            NSLog(@"removeitematpath %@ error :%@", createPath, error);        }    }    [fileManager createDirectoryAtPath:createPath withIntermediateDirectories:YES attributes:nil error:nil];}