ios - Swift 4 中的布局 anchor

Question

我正在努力更新/简化我关于自动布局与 NSConstraints 的代码，但现在似乎让我感到困惑。

我有一些 Swift 3 代码，可以在轻按按钮时在 UIView 中滑动，但是 UIView 由 NSconstraints 控制并且工作正常。 -

@IBAction func rightFlyOutButton(_ sender: Any) {
        if (rightFlyOutShowing) {
            if UI_USER_INTERFACE_IDIOM() == UIUserInterfaceIdiom.pad {
                leftFlyOutLeadingConstraint.constant = 25
            } else {
                leftFlyOutLeadingConstraint.constant = 15
            }
            rightFlyOutTrailingConstraint.constant = rightFlyOut.frame.width * 0.93
            UIView.animate(withDuration: 0.4, animations: {self.view.layoutIfNeeded()})
        } else {
            if UI_USER_INTERFACE_IDIOM() == UIUserInterfaceIdiom.pad {
                rightFlyOutTrailingConstraint.constant = 25
            } else {
                rightFlyOutTrailingConstraint.constant = 15
            }
            UIView.animate(withDuration: 0.4, animations: {self.view.layoutIfNeeded()})
        }
        rightFlyOutShowing = !rightFlyOutShowing
    }

尝试使用 AutoLayout 和 Layout Anchors，我想到了这个 -

@IBAction func rightFlyOutButton(_ sender: Any) {
        rightFlyOut.rightAnchor.constraint(equalTo: view.rightAnchor).isActive = true
        rightFlyOut.widthAnchor.constraint(equalTo: view.widthAnchor, multiplier: 0.93).isActive = true
        UIView.animate(withDuration: 0.4, animations: {self.view.layoutIfNeeded()})
    }

这会返回大量错误 -

[LayoutConstraints] Unable to simultaneously satisfy constraints.
    Probably at least one of the constraints in the following list is one you don't want. 
    Try this: 
        (1) look at each constraint and try to figure out which you don't expect; 
        (2) find the code that added the unwanted constraint or constraints and fix it. 
    (Note: If you're seeing NSAutoresizingMaskLayoutConstraints that you don't understand, refer to the documentation for the UIView property translatesAutoresizingMaskIntoConstraints) 
(
    "<NSAutoresizingMaskLayoutConstraint:0x6000000949b0 h=-&& v=-&& FasteM.UIViewX:0x7fed7140c600.width == 0.500741*UIView:0x7fed7161d760.width + 150.222   (active)>",
    "<NSLayoutConstraint:0x6000000900e0 FasteM.UIViewX:0x7fed7140c600.width == 0.93*UIView:0x7fed7161d760.width   (active)>",
    "<NSLayoutConstraint:0x600000095a90 'UIView-Encapsulated-Layout-Width' UIView:0x7fed7161d760.width == 375   (active)>"
)

我的逻辑是我将 View 的右边缘锚定到父 View 并指定实际 View 的宽度(即父 View 的 93%。

我确信这是我遗漏的一个简单错误，但我将不胜感激任何指向正确方向的指示。

TIA

Answer 1

第二种方法的问题是每次点击都会创建其他约束，这会与旧的相同约束发生冲突，因此您应该在任何地方创建这些约束，获取对它们的引用并在您更改它们的常量时以最正确的方式做