如何在表格单元格中显示进度？

Posted 2023-02-24

【中文标题】如何在表格单元格中显示进度？

【英文标题】：How to show progress in table cell?

【发布时间】：2016-04-01 14:00:47

【问题描述】：

我从服务器下载一个文件。文件下载时，我想在表格单元格中显示进度百分比。我该怎么做？

下载文件代码

NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
NSString *documentsDirectory = [paths objectAtIndex:0];
NSString *filePath = [documentsDirectory stringByAppendingPathComponent:@"01.mp3"];
dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^
BOOL fileExists = [[NSFileManager defaultManager] fileExistsAtPath:filePath isDirectory:NO];

if (!fileExists) 

    NSString *stringURL = @"https://drive.google.com/uc?export=download&id=0B6zMam2kAK39X0FOaUJXVDUwOHc";
    NSURL  *url = [NSURL URLWithString:stringURL];
    NSData *urlData = [NSData dataWithContentsOfURL:url];
    [urlData writeToFile:filePath atomically:YES];


);
self.audioPlayer = [[AVAudioPlayer alloc] initWithContentsOfURL:[NSURL URLWithString:filePath] error:nil];

【参考方案1】：

[NSData dataWithContentsOfUrl] 无法做到这一点。您需要一个库，例如 AFNetworking

见How to get download progress in AFNetworking 2.0?

【参考方案2】：

创建自定义单元格 XIB 文件并在其上添加进度条

在您的视图控制器中开始下载，并访问进度条并在 didReceiveData 方法中设置进度

我刚刚在视图控制器中创建，您需要将它与表视图方法一起使用

代码示例：

   @interface ViewController ()<NSURLConnectionDataDelegate>

    //Put these in custom cell file
    @property (weak, nonatomic) IBOutlet UIProgressView *progressView;
    @property (weak, nonatomic) IBOutlet UIImageView *imageView;

    @property (strong, nonatomic) NSURLConnection *connectionManager;
    @property (strong, nonatomic) NSMutableData *downloadedMutableData;
    @property (strong, nonatomic) NSURLResponse *urlResponse;

    @end

    @implementation ViewController

    - (void)viewDidLoad
    
        [super viewDidLoad];

        //Start download request logic
        self.downloadedMutableData = [[NSMutableData alloc] init];
        NSURLRequest *urlRequest = [NSURLRequest requestWithURL:[NSURL URLWithString:@"https://www.planwallpaper.com/static/images/63906_1_BdhSun5.jpg"]
                                                    cachePolicy:NSURLRequestReloadIgnoringLocalCacheData
                                                timeoutInterval:60.0];
        self.connectionManager = [[NSURLConnection alloc] initWithRequest:urlRequest delegate:self];
    



    #pragma mark - Delegate Methods
    -(void)connection:(NSURLConnection *)connection didReceiveResponse:(NSURLResponse *)response 
        NSLog(@"%lld", response.expectedContentLength);
        self.urlResponse = response;
    

//Show progress download while receiving data 
    -(void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)data 
        [self.downloadedMutableData appendData:data];
        self.progressView.progress = ((100.0/self.urlResponse.expectedContentLength)*self.downloadedMutableData.length)/100;
        if (self.progressView.progress == 1) 
            self.progressView.hidden = YES;
         else 
            self.progressView.hidden = NO;
        
        NSLog(@"%.0f%%", ((100.0/self.urlResponse.expectedContentLength)*self.downloadedMutableData.length));
    

    -(void)connectionDidFinishLoading:(NSURLConnection *)connection 
        NSLog(@"Finished");
        self.imageView.image = [UIImage imageWithData:self.downloadedMutableData];
    

结果看起来像

【讨论】：

如果我使用NSURLRequest *urlRequest = [NSURLRequest requestWithURL:[NSURL URLWithString:@"https://drive.google.com/uc?export=download&id=0B6zMam2kAK39Zm5LUTctZXNLUlE»] Progress 不起作用。为什么？

请参阅我们需要一个委托方法来获取下载进度 所以我使用了 NSURLConnection 类，因为它有 didReceiveData 我更新进度条的委托方法