爲什麼在導航欄中未顯示uiactivity指示器

Question

UIActivityIndicatorView *activityView = [[UIActivityIndicatorView alloc] initWithFrame:CGRectMake(0, 0, 14, 14)]; 
[activityView sizeToFit]; 
[activityView setAutoresizingMask:(UIViewAutoresizingFlexibleLeftMargin | UIViewAutoresizingFlexibleRightMargin | UIViewAutoresizingFlexibleTopMargin | UIViewAutoresizingFlexibleBottomMargin)]; 

activityView.hidesWhenStopped = NO; 

self.navigationItem.rightBarButtonItem = [[UIBarButtonItem alloc] initWithCustomView:activityView]; 

[activityView startAnimating]; 

uiactivity指示器未顯示在右上角的原因是什麼？什麼都不顯示在右上方的導航欄中。

Answer 1

因爲你不分配活動指示燈的顏色 指定顏色的話，我會在導航欄中顯示

activityView.color = [UIColor blackColor]; 

Answer 2

你需要設置活動的指標類型...試試這個：

UIActivityIndicatorView * activityView = [[UIActivityIndicatorView alloc] initWithActivityIndicatorStyle:UIActivityIndicatorViewStyleWhite]; 
activityView.frame = CGRectMake(0, 0, 14, 14); 
[activityView sizeToFit]; 
[activityView setAutoresizingMask:(UIViewAutoresizingFlexibleLeftMargin | UIViewAutoresizingFlexibleRightMargin | UIViewAutoresizingFlexibleTopMargin | UIViewAutoresizingFlexibleBottomMargin)]; 

activityView.hidesWhenStopped = NO; 

self.navigationItem.rightBarButtonItem = [[UIBarButtonItem alloc] initWithCustomView:activityView]; 

[activityView startAnimating];