iphone - UIProgressView 不显示

Question

我有一个 UIProgressView 我想在我的 GLKViewController 上运行，而其余代码正在由 iOS 加载。我已将 UIProgressView 放入我的“viewDidLoad”方法中。在 viewDidLoad 方法加载所有代码之前，UIProgressView 不会显示。如何让 UIProgressView 在调用 viewDidLoad 方法时立即显示并在 viewDidLoad 方法完成时结束？

- (void)viewDidLoad
{
    [super viewDidLoad];

    // Progress Bar
    [threadProgressView setProgress: 0.0];    
    [self performSelectorOnMainThread:@selector(updateProgressBar) withObject:nil waitUntilDone:NO];

    // Disbale iPhone from locking
    [[UIApplication sharedApplication] setIdleTimerDisabled: YES];

    // Set up context to use Open GL ES
    self.context = [[EAGLContext alloc] initWithAPI:kEAGLRenderingAPIOpenGLES2];

    if (!self.context) {
        NSLog(@"Failed to create ES context");
    }

    // Create a view to display the Open GL ES content
    GLKView *view = (GLKView *)self.view;
    view.context = self.context;
    view.drawableDepthFormat = GLKViewDrawableDepthFormat24;

    /******** Default Settings **********/
    m_kf            = 0;                                    // The current keyframe ID.
    m_avPos         = GLKVector3Make(0.0f, 0.0f, -35.0f);   // Where to put the avata.
    m_camPos        = GLKVector3Make(0.0f, 10.0f, -35.0f);  // The camera orbits this point.
    m_camDist       = 30.0f;                                // Distance of camera from the orbit point.

    /******** Set up open gl ***********/
    [self setupGL];

    /********* TOUCH IMPLEMENTATION *********/

    // Pinch recongizer detects pinches and is used to zoom in/out
    UIPinchGestureRecognizer *pinchRecognizer = [[UIPinchGestureRecognizer alloc] initWithTarget:self action:@selector(pinchDetected:)];
    [self.view addGestureRecognizer:pinchRecognizer];

    // Pan recognizer, used to rotate around the x and y axis
    UIPanGestureRecognizer *panRecognizer = [[UIPanGestureRecognizer alloc] initWithTarget:self action:@selector(panDetected:)];
    [self.view addGestureRecognizer:panRecognizer];

    /********* END TOUCH IMPLEMENTATION *********/

}

Answer 1

How can I get the UIProgressView to display as soon as the viewDidLoad method is called and end when the viewDidLoad method is finished?

当 viewDidLoad 被调用时， View 还没有出现在屏幕上。在 viewDidLoad 之后，您将看到 viewWillAppear 然后调用 viewDidAppear。

而且如果你有一个长时间运行的 viewDidLoad 它会阻塞你的主线程，所以你的进度条不会得到更新。
当你这样做时:

 [self performSelectorOnMainThread:@selector(updateProgressBar) withObject:nil waitUntilDone:NO];    

由于您在主线程上，指定 waitUntilDone 会将您的请求排队并稍后处理，可能在您的 viewDidLoad 完成之后。

为了做你想做的事，你将需要更多的异步代码。