我在一个UIViewController中设置了一些布局约束,这在iOS8上运行良好。但是当我在iOS7上运行时,出现了以下错误:
*** Assertion failure in -[UIView layoutSublayersOfLayer:], /SourceCache/UIKit_Sim/UIKit-2935.137/UIView.m:8803
这是我的代码:
class DatacenterIndicatorViewController: UIViewController {
let sideMargins:Float = 12.0
var dataCenterPollingLabel:UILabel = UILabel()
var dataCenterAlarmLabel:UILabel = UILabel()
//MARK: - Life cycle
override func viewDidLoad() {
super.viewDidLoad()
self.view.addSubview(dataCenterPollingLabel)
self.view.addSubview(dataCenterAlarmLabel)
}
override func viewDidLayoutSubviews() {
super.viewDidLayoutSubviews()
self.reloadData()
}
func reloadData() {
self.setupAlarmLabel()
self.setupPollingLabel()
self.generateConstraints()
}
func setupPollingLabel() {
// some graphic setup
}
func setupAlarmLabel() {
// some graphic setup
}
func generateConstraints() {
self.dataCenterPollingLabel.setTranslatesAutoresizingMaskIntoConstraints(false)
self.dataCenterAlarmLabel.setTranslatesAutoresizingMaskIntoConstraints(false)
self.view.addConstraint(NSLayoutConstraint(item: dataCenterPollingLabel, attribute: NSLayoutAttribute.CenterY, relatedBy: NSLayoutRelation.Equal, toItem: self.view, attribute: NSLayoutAttribute.CenterY, multiplier: 1.0, constant: 0.0))
self.view.addConstraint(NSLayoutConstraint(item: dataCenterAlarmLabel, attribute: NSLayoutAttribute.CenterY, relatedBy: NSLayoutRelation.Equal, toItem: self.view, attribute: NSLayoutAttribute.CenterY, multiplier: 1.0, constant: 0.0))
self.view.addConstraint(NSLayoutConstraint(item: dataCenterAlarmLabel, attribute: NSLayoutAttribute.Width, relatedBy: NSLayoutRelation.Equal, toItem: dataCenterPollingLabel, attribute: NSLayoutAttribute.Width, multiplier: 1.0, constant: 0.0))
self.view.addConstraints(NSLayoutConstraint.constraintsWithVisualFormat(NSString(format:"H:|-==%f-[dataCenterPollingLabel]-==%f-[dataCenterAlarmLabel]-==%f-|", sideMargins, sideMargins, sideMargins), options: NSLayoutFormatOptions.allZeros, metrics: nil, views: ["dataCenterPollingLabel": dataCenterPollingLabel, "dataCenterAlarmLabel": dataCenterAlarmLabel]))
}
}
我的代码出了什么问题?我甚至不知道去哪里找错误,所有东西看起来都很好。