-(void)photoFile {
    
    //此处首先指定了图片存取路径（默认写到应用程序沙盒 中）
    NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory,NSUserDomainMask, YES);

    //并给文件起个文件名
    NSString *uniquePath=[[paths objectAtIndex:0] stringByAppendingPathComponent:@"pin"];
    BOOL blHave=[[NSFileManager defaultManager] fileExistsAtPath:uniquePath];
    if (blHave) {
        NSLog(@"already have");
        return ;
    }
    //此处的方法是将图片写到Documents文件中 如果写入成功会弹出一个警告框,提示图片保存成功
    NSString *strPathOld = [[NSBundle mainBundle] pathForResource:@"pin" ofType:@"png"];
    NSData *data = [NSData dataWithContentsOfFile:strPathOld];
    BOOL result = [data writeToFile:uniquePath atomically:YES];
    if (result) {
        NSLog(@"success");
    }else {
        NSLog(@"no success");
    }
    
}

// 删除沙盒里的文件
-(void)deleteFile {
    NSFileManager* fileManager=[NSFileManager defaultManager];
    NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory,NSUserDomainMask, YES);
    
    //文件名
    NSString *uniquePath=[[paths objectAtIndex:0] stringByAppendingPathComponent:@"pin.png"];
    BOOL blHave=[[NSFileManager defaultManager] fileExistsAtPath:uniquePath];
    if (!blHave) {
        NSLog(@"no  have");
        return ;
    }else {
        NSLog(@" have");
        BOOL blDele= [fileManager removeItemAtPath:uniquePath error:nil];
        if (blDele) {
            NSLog(@"dele success");
        }else {
            NSLog(@"dele fail");
        }

    }
}

// 图片

UIImage *img = [UIImage imageNamed:@"1.png"];
NSData* data = UIImagePNGRepresentation(img);


//向沙盒里 写入文件夹，并向文件夹里 写入东西

 NSFileManager *fileManager = [NSFileManager defaultManager];
    NSString *document = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) objectAtIndex:0];
    NSString *folder = [document stringByAppendingPathComponent:@"folder"];
    NSString *filePath = [folder stringByAppendingPathComponent:@"test.png"];
    
    if (![fileManager fileExistsAtPath:folder]) {
        BOOL blCreateFolder= [fileManager createDirectoryAtPath:folder withIntermediateDirectories:NO attributes:nil error:NULL];  
        if (blCreateFolder) {
            NSLog(@" folder success");
        }else {
            NSLog(@" folder fial");
        }
    }else {
        NSLog(@" 沙盒文件已经存在");
    }
    
    if (![fileManager fileExistsAtPath:filePath]) {
        NSString *strPathOld = [[NSBundle mainBundle] pathForResource:@"test" ofType:@"png"];
        NSData *data = [NSData dataWithContentsOfFile:strPathOld];
        
        BOOL result = [data writeToFile:filePath atomically:YES];
        
        if (result) {
            NSLog(@"success");
        }else {
            NSLog(@"no success");
        }
    }

//得到沙盒文件夹 下的所有文件
NSFileManager *fileManager = [NSFileManager defaultManager];
    
    NSString *document=[NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) objectAtIndex:0];
    NSString *folder =[document stringByAppendingPathComponent:@"folder"];
    NSArray *fileList ;
    fileList =[fileManager contentsOfDirectoryAtPath:folder error:NULL];
    
    
    
    for (NSString *file in fileList) {
        NSLog(@"file=%@",file);
        NSString *path =[folder stringByAppendingPathComponent:file];
        NSLog(@"得到的路径=%@",path);
    }