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我试图用超级视图中的按钮来中心我的子视图。所以我希望子视图的中心是超视图的中心。我试图用下面的代码:超级视图中的中心视图
override func viewDidLoad() {
self.view.backgroundColor = UIColor.redColor()
var menuView = UIView()
var newPlayButton = UIButton()
//var newPlayImage = UIImage(named: "new_game_button_5cs")
var newPlayImageView = UIImageView(image: UIImage(named: "new_game_button_5cs"))
newPlayButton.frame = CGRectMake(0, 0, newPlayImageView.frame.width, newPlayImageView.frame.height)
newPlayButton.setImage(newPlayImage, forState: .Normal)
newPlayButton.backgroundColor = UIColor.whiteColor()
menuView.backgroundColor = UIColor.whiteColor()
menuView.addSubview(newPlayButton)
menuView.addConstraint(
NSLayoutConstraint(item: self.view,
attribute: .CenterX,
relatedBy: .Equal,
toItem: menuView,
attribute: .CenterX,
multiplier: 1, constant: 0)
)
}
不幸的是,当我尝试运行它时程序中断。 (线程1:信号SIGABRT)
添加一个异常断点,看看它崩溃了:https://developer.apple.com/library/ios/recipes/xcode_help-breakpoint_navigator/articles/adding_an_exception_breakpoint.html – 2014-12-02 10:04:22