objective-c - UIActivityIndi​​cator没有立即显示

Question

由于某种原因，我无法立即显示 Activity 指示器。也许有人能明白为什么？

UIActivityIndicatorView *spinner = [[UIActivityIndicatorView alloc] initWithActivityIndicatorStyle:UIActivityIndicatorViewStyleWhiteLarge];
spinner.center = self.view.center; 
_active = spinner;
[self.view addSubview:spinner];
[spinner startAnimating];
@try {

    [self connectToServerUsingStream:ip portNo:port];
    NSString *text = @"test";
    const uint8_t *str =
    (uint8_t *) [text cStringUsingEncoding:NSASCIIStringEncoding];
    [self writeToServer:str];

}
@catch (NSException * e) {
    NSLog(@"Exception: %@", e);
}

微调框仅显示，然后与服务器建立连接，然后再不显示。有任何想法吗？

Answer 1

使用下面的更新代码。我认为它将起作用。

UIActivityIndicatorView *spinner = [[UIActivityIndicatorView alloc] initWithActivityIndicatorStyle:UIActivityIndicatorViewStyleWhiteLarge];
spinner.center = self.view.center; 
 _active = spinner; 
[self.view addSubview:spinner]; 
[spinner startAnimating]; 
[self performSelector:@selector(performTask) withObject:nil afterDelay:0.0];

- (void)performTask {
     @try {
         [self connectToServerUsingStream:ip portNo:port];
         NSString *text = @"test";
         const uint8_t *str =
         (uint8_t *) [text cStringUsingEncoding:NSASCIIStringEncoding];
         [self writeToServer:str];

     }
     @catch (NSException * e) {
         NSLog(@"Exception: %@", e);
     } 
}