iOS 9 View Not appearing

问题

I have noticed a that a uibutton is not showing in my app when run in iOS 9 (works fine in earlier OS versions). I know several have noticed a similar issue with storyboards (https://forums.developer.apple.com/thread/14003), though I am not using those and am instead building my view programmatically. There is no autolayout or autoresizingmask to worry about.

UIButton * button = [UIButton buttonWithType:UIButtonTypeCustom];
button.frame = CGRectMake(SUG_MARGIN, self.mainView.bounds.size.height - 40 - margin, self.mainView.bounds.size.width-margin*2, 40);
[button setTitle:NSLocalizedString(@"...", nil) forState:UIControlStateNormal];
button.titleLabel.font = //...;
button.backgroundColor = //...;
[self.mainView addSubview:button];

NSLog(@"main:%@\nadd:%@\nsuper:%@", NSStringFromCGRect(self.mainView.frame), NSStringFromCGRect(button.frame), button.superview);

That nslog shows everything set up correctly.

I have similar buttons all over the app, but this is the only one that is not appearing, which is why I am scratching my head.

回答1:

Refactored code to assign only measure frames in viewWillLayoutSubviews and it now works. strange.

来源：https://stackoverflow.com/questions/32976447/ios-9-view-not-appearing