为什么导航栏中未显示 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];

右上角没有显示uiactivity指示器是什么原因？右上角的导航栏没有显示任何内容。

Answer 1

因为你没有指定Activity指标的颜色 分配颜色然后我将在导航栏中显示

activityView.color = [UIColor blackColor];

Answer 2

您需要设置 activity 指标的类型...试试这个：

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];