ios - Swift:自定义 UIView 未根据约束调整大小

Question

我创建了一个从 XIB 文件加载的自定义 UIView。然后我将 View 添加到堆栈 View ，并在项目上设置宽度约束。

如果我从 Storyboard 中执行此操作，它会完美地工作，但是如果我从 Swift 中执行此操作，我将无法使 View 拉伸(stretch)到约束。 stackview 正在为 View 分配空间，但 View 不会拉伸(stretch)到该空间。

自定义 View swift代码:

import Foundation
import UIKit

@IBDesignable class TabButton: UIView {

@IBOutlet weak var label: UILabel!

@IBInspectable var TabText: String? {
    get {
        return label.text
    }
    set(TabText) {
        label.text = TabText
        label.sizeToFit()
    }
}

override func intrinsicContentSize() -> CGSize {
    return CGSize(width: UIViewNoIntrinsicMetric, height: UIViewNoIntrinsicMetric)
}

override init(frame: CGRect) {
    // 1. setup any properties here

    // 2. call super.init(frame:)
    super.init(frame: frame)

    // 3. Setup view from .xib file
    xibSetup()
}

required init(coder aDecoder: NSCoder) {
    // 1. setup any properties here

    // 2. call super.init(coder:)
    super.init(coder: aDecoder)!

    // 3. Setup view from .xib file
    xibSetup()
}

// Our custom view from the XIB file
var view: UIView!

func xibSetup() {
    view = loadViewFromNib()

    // use bounds not frame or it'll be offset
    view.frame = bounds

    // Make the view stretch with containing view
    view.autoresizingMask = [.FlexibleWidth, .FlexibleHeight]

    // Adding custom subview on top of our view (over any custom drawing > see note below)
    addSubview(view)
}

func loadViewFromNib() -> UIView {

    let bundle = NSBundle(forClass: self.dynamicType)
    let nib = UINib(nibName: "TabButton", bundle: bundle)
    let view = nib.instantiateWithOwner(self, options: nil)[0] as! UIView

    self.roundCorners([.TopLeft, .TopRight], radius: 10)

    return view
}
}

这是将 View (tabButton) 添加到堆栈 View (tabBar) 的 View Controller :

@IBOutlet weak var tabBar: UIStackView!

override func viewDidLoad() {
    super.viewDidLoad()

    let tabButton = TabButton(frame: CGRectZero)
    tabButton.label.text = "All Videos"

    tabButton.backgroundColor = UIColor.blackColor()

    let widthConstraint = NSLayoutConstraint(item: tabButton, attribute: NSLayoutAttribute.Width, relatedBy: NSLayoutRelation.Equal, toItem: nil, attribute: NSLayoutAttribute.NotAnAttribute, multiplier: 1, constant: 100)
    tabButton.addConstraint(widthConstraint)

    tabBar.insertArrangedSubview(tabButton, atIndex: 0)
}

我希望 tabButton“忽略”它的框架并根据堆栈 View 的高度和我设置的宽度约束调整大小。

我错过了什么？

更新:

我对自定义 View 的限制(基本上只是一个带标签的 View - 但我也计划将其用于更复杂的布局):

Answer 1

试试这个:

let widthConstraint = NSLayoutConstraint (item: your_item_here, attribute: NSLayoutAttribute.Width, relatedBy: NSLayoutRelation.Equal, toItem: nil, attribute: NSLayoutAttribute.NotAnAttribute, multiplier: 1, constant: your_value_here)
self.view.addConstraint(widthConstraint)