1.获取Caches 文件夹路径。

NSString *pathDocuments = [NSSearchPathForDirectoriesInDomains(NSCachesDirectory, NSUserDomainMask, YES) objectAtIndex:0];

NSLog:    /Users/sundongri/Library/Developer/CoreSimulator/Devices/649D1D25-FA3F-4EB2-96FC-92AF6A6B9D97/data/Containers/Data/Application/5668FC61-F42D-4C07-9761-24577C5327CE/Library/Caches

2.在Caches 文件夹下面 建一个子文件夹便于管理！

NSString *imagePath = [NSString stringWithFormat:@"%@/Media", pathDocuments];

[[NSFileManager defaultManager] createDirectoryAtPath:imagePath withIntermediateDirectories:YES attributes:nil error:nil];

NSLog:  /Users/sundongri/Library/Developer/CoreSimulator/Devices/649D1D25-FA3F-4EB2-96FC-92AF6A6B9D97/data/Containers/Data/Application/5668FC61-F42D-4C07-9761-24577C5327CE/Library/Caches/Media

文件名字为Media。

3.获取NSData

//工程里的视频

NSString * path = [[NSBundle mainBundle] pathForResource:@"D0024" ofType:@"mp4"];

//转化成NSData

NSData *videoMy=[NSData dataWithContentsOfFile:path];

//初始化一个动态的data 容器 

NSMutableData *videoData =[NSMutableData data];

//初始化要用这种  不要用videoData=nil;

[videoData setData:[NSData data]];

//添加Data 也可以用来接收下载过来的Data，因为下载的数据是一段一段过来的 所以appendData 不断的加（本地的数据就一次行加进来了）

[videoData appendData:videoMy];

//imagePath 是咱们创建的media文件夹拼上DJI_0024.mp4 ，最后结尾为media/DJI_0024.mp4

NSString *filePath = [imagePath stringByAppendingPathComponent:@"DJI_0024.mp4"];

//接下来就是写进文件 然后播放本地文件

BOOL isSuccess = [videoData writeToFile:filePath atomically:YES];

if (isSuccess) {

NSLog(@"能写进去");

}

else{

NSLog(@"不成功");

}

NSURL *url = [NSURL fileURLWithPath:filePath];

AVPlayerViewController * play = [[AVPlayerViewController alloc]init];

play.player = [[AVPlayer alloc]initWithURL:url];

[self presentViewController:play animated:YES completion:nil];

PS：下载视频的时候如果要算下载进度，如果（总字节）fileSizeInBytes／1048576 后面加个M 就是一共有多少兆了！！