UIActivityIndicatorView ---- 加载进度

UIActivityIndicatorView可以用于显示某项工作在进行中，比如加载进度。在iphone中应用很广泛

用法一：只显示不停旋转的进度滚轮指示器。
//显示进度滚轮指示器
-(void)showWaiting {

progressInd=[[UIActivityIndicatorView alloc]initWithActivityIndicatorStyle:
UIActivityIndicatorViewStyleWhiteLarge];
progressInd.center=CGPointMake(self.view.center.x,240);
[self.navigationController.view addSubview:progressInd];
[progressInd startAnimating];
}
//消除滚动轮指示器
-(void)hideWaiting
{
[progressInd stopAnimating];
}

用法二：带有半透明背景的进度轮指示器。

//显示进度滚轮指示器
-(void)showWaiting:(UIView *)parent {

    int width = 32, height = 32;

    CGRect frame = CGRectMake(100, 200, 110, 70) ;//[parent frame]; //[[UIScreen mainScreen] applicationFrame];
    int x = frame.size.width;
    int y = frame.size.height;

    frame = CGRectMake((x - width) / 2, (y - height) / 2, width, height);
    UIActivityIndicatorView* progressInd = [[UIActivityIndicatorView alloc]initWithFrame:frame];
    [progressInd startAnimating];
    progressInd.activityIndicatorViewStyle = UIActivityIndicatorViewStyleWhiteLarge;

frame = CGRectMake((x - 70)/2, (y - height) / 2 + height, 80, 20);
UILabel *waitingLable = [[UILabel alloc] initWithFrame:frame];
waitingLable.text = @"Loading...";
waitingLable.textColor = [UIColor whiteColor];
waitingLable.font = [UIFont systemFontOfSize:15];
waitingLable.backgroundColor = [UIColor clearColor];

    frame = CGRectMake(100, 200, 110, 70) ;//[parent frame];
    UIView *theView = [[UIView alloc] initWithFrame:frame];
    theView.backgroundColor = [UIColor blackColor];
    theView.alpha = 0.7;

    [theView addSubview:progressInd];
[theView addSubview:waitingLable];

    [progressInd release];
[waitingLable release];

    [theView setTag:9999];
    [parent addSubview:theView];
    [theView release];
}

//消除滚动轮指示器
-(void)hideWaiting
{
[[self.view viewWithTag:9999] removeFromSuperview];
}

补充：移动开发 , IOS ,