路径的拼接问题

1. stringByAppendingString (是在后面加后缀的意思)

在模拟器上好用,真机上提示无法进行操作,改成第二种写法即可.

2.stringByAppendingPathComponent(是在后面加上“／”号连接 让它成为完整的路径)

附上下载代码:(协议可以改成block)

// 1. 建立请求
    NSURLRequest *request = [NSURLRequest requestWithURL:[NSURL URLWithString:model.music_url]];
    
    AFHTTPRequestOperation *operation = [[AFHTTPRequestOperation alloc] initWithRequest:request];
    // 下载 存储路径
    NSString *path = [[NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) lastObject] stringByAppendingString:model.path];
    
    operation.outputStream = [NSOutputStream outputStreamToFileAtPath:path append:NO];
    
    // 设置下载进程块代码
    /*
     bytesRead                      当前一次读取的字节数(100k)
     totalBytesRead                 已经下载的字节数(4.9M）
     totalBytesExpectedToRead       文件总大小(5M)
     */
    [operation setDownloadProgressBlock:^(NSUInteger bytesRead, long long totalBytesRead, long long totalBytesExpectedToRead) {
        
        // 设置进度条的百分比
        CGFloat precent = (CGFloat)totalBytesRead / totalBytesExpectedToRead;
//        NSLog(@"%f", precent);
        if ([self.delegate respondsToSelector:@selector(downloadMusicProgress:)]) {
            [self.delegate downloadMusicProgress:precent];
        }
    }];
    
    // 设置下载完成操作
    [operation setCompletionBlockWithSuccess:^(AFHTTPRequestOperation *operation, id responseObject) {
        if ([self.delegate respondsToSelector:@selector(downloadMusic:success:)]) {
            [self.delegate downloadMusic:model success:nil];
        }
        
    } failure:^(AFHTTPRequestOperation *operation, NSError *error) {
        if ([self.delegate respondsToSelector:@selector(downloadMusic:error:)]) {
            [self.delegate downloadMusic:model error:error];
        }
    }];
    NSLog(@"加入队列");
    [_downloadQueue addOperation:operation];