ios - 过程中的 UIProgressView 栏

Question

我想在我的应用程序中实现一个进度条。发生的过程是应用程序将一个目录复制到 iOS 文档目录中。通常需要 7-10 秒(iPhone 4 测试)。我对进度条的理解是你在事情发生时更新进度条。但是根据目录代码的复制，我不确定如何知道它有多远。

任何人都可以就如何做到这一点提供任何建议或示例吗？下面是进度条代码和目录代码的复制。

谢谢!

UIProgressView *progressView = [[UIProgressView alloc] initWithProgressViewStyle:  UIProgressViewStyleBar];
progressView.progress = 0.75f;
[self.view addSubview: progressView];
[progressView release];


 //Takes 7-10 Seconds. Show progress bar for this code
if (![fileManager fileExistsAtPath:dataPath]) {
    NSString *bundlePath = [[NSBundle mainBundle] bundlePath];
    NSString *imageDataPath = [bundlePath stringByAppendingPathComponent:_dataPath];
    if (imageDataPath) {
        [fileManager copyItemAtPath:imageDataPath toPath_:dataPath error:nil];
    }
}

Answer 1

在你的 .h 文件中定义 NSTimer *timer

if (![fileManager fileExistsAtPath:dataPath]) {
    NSString *bundlePath = [[NSBundle mainBundle] bundlePath];
    NSString *imageDataPath = [bundlePath stringByAppendingPathComponent:_dataPath];
    timer = [NSTimer timerWithTimeInterval:0.5 target:self selector:@selector(updateProgressView) userInfo:nil repeats:YES];
    [timer fire];  
    if (imageDataPath) {
        dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
            [fileManager copyItemAtPath:imageDataPath toPath_:dataPath error:nil];
        };
    }
}

并添加这个方法

- (void) updateProgressView{
    NSString *bundlePath = [[NSBundle mainBundle] bundlePath];
    NSString *imageDataPath = [bundlePath stringByAppendingPathComponent:_dataPath];
    NSData *allData = [NSData dataWithContentsOfFile:imageDataPath];
    NSData *writtenData = [NSData dataWithContentsOfFile:dataPath];
    float progress = [writtenData length]/(float)[allData length];
    [pro setProgress:progress];
    if (progress == 1.0){
         [timer invalidate];
    }
}