背景和目标

Goal:我想旋转和翻转UITextView. (Why: see my 上一个问题 https://stackoverflow.com/questions/28544714/how-do-you-make-a-vertical-text-uilabel-and-uitextview-for-ios-in-swift)

Problem:如果我直接在UITextView，由于某种未知的原因，文本布局变得混乱。

解决方案：放在UITextView in a UIView容器，然后对容器进行转换。

新问题：旋转视图上的自动布局（或任何类型的布局）变为非常头疼 https://stackoverflow.com/questions/30841064/are-rotated-views-compatible-with-auto-layout.

建议的解决方案：制作一个子类UIView充当旋转和翻转的附加容器UIView。然后自动布局应该在这个自定义视图上工作。

目前的问题

当所有内容第一次出现时它就会起作用（UITextView有黄色背景）：

但是当方向发生变化时，会发生以下情况（蓝色是子类UIView背景，在IB中设置）：

如果我禁用rotationView.addSubview(textView)线，然后旋转容器视图（红色）可以很好地重新定位自身，即使方向发生变化：

所以问题一定出在我添加的位置UITextView。但我该怎么做呢？

Code

class MongolTextView: UIView {

    // properties
    var rotationView: UIView!
    var textView: UITextView!

    // This method gets called if you create the view in the Interface Builder
    required init(coder aDecoder: NSCoder) {
        super.init(coder: aDecoder)
    }

    // This method gets called if you create the view in code
    override init(frame: CGRect){
        super.init(frame: frame)
        self.setup()
    }

    override func awakeFromNib() {
        super.awakeFromNib()
        self.setup()
    }

    func setup() {

        rotationView = UIView(frame: self.frame)
        rotationView.backgroundColor = UIColor.redColor()
        self.addSubview(rotationView)

        textView = UITextView(frame: CGRectZero)
        textView.backgroundColor = UIColor.yellowColor()
        textView.text = "This is some text This is some text This is some text This is some text This is some text This is some text This is some text This is some text This is some text This is some text This is some text This is some text This is some text This is some text This is some text This is some text This is some text This is some text This is some text This is some text This is some text This is some text This is some text This is some text This is some text This is some text This is some text This is some text "

    }

    override func layoutSubviews() {
        super.layoutSubviews()

        // set the size of the rotation container view
        let width = self.bounds.width
        let height = self.bounds.height
        rotationView.frame = CGRect(origin: CGPoint(x: CGFloat(0), y: CGFloat(0)), size: CGSize(width: height, height: width))

        textView.frame = rotationView.bounds // Problem lines here???
        rotationView.addSubview(textView)    // Problem lines here???

        // rotate, translate, and flip the container view
        var rotation = CGAffineTransformMakeRotation(CGFloat(-M_PI_2))
        // the following translation repositions the top left corner at the origin of the superview
        var translation = CGAffineTransformMakeTranslation((rotationView.bounds.height / 2)-(rotationView.bounds.width / 2), (rotationView.bounds.width / 2)-(rotationView.bounds.height / 2))
        var rotationAndTranslation = CGAffineTransformConcat(rotation, translation)
        var transformPlusScale = CGAffineTransformScale(rotationAndTranslation, CGFloat(-1), CGFloat(1))

        rotationView.transform = transformPlusScale

    }
}

如果我不能让这个工作......

虽然我现在已经碰壁了，但我的下一步计划是克服drawRect()进行转换。但这不是我的第一选择，因为这样做可能会降低性能。

问题中的代码的问题似乎是转换不断相互添加。为了解决这个问题，解决方案是每次都重置变换，即将其设置为恒等变换。

rotationView.transform = CGAffineTransformIdentity

这是显示关键部分的部分实现。

import UIKit
@IBDesignable class UIVerticalTextView: UIView {

    var textView = UITextView()
    let rotationView = UIView()

    var underlyingTextView: UITextView {
        get {
            return textView
        }
        set {
            textView = newValue
        }
    }

    required init?(coder aDecoder: NSCoder) {
        super.init(coder: aDecoder)
    }

    override init(frame: CGRect){
        super.init(frame: frame)
        self.setup()
    }

    override func awakeFromNib() {
        super.awakeFromNib()
        self.setup()
    }

    func setup() {

        rotationView.backgroundColor = UIColor.redColor()
        textView.backgroundColor = UIColor.yellowColor()
        self.addSubview(rotationView)
        rotationView.addSubview(textView)

        // could also do this with auto layout constraints
        textView.frame = rotationView.bounds
    }

    override func layoutSubviews() {
        super.layoutSubviews()

        rotationView.transform = CGAffineTransformIdentity // *** key line ***

        rotationView.frame = CGRect(origin: CGPointZero, size: CGSize(width: self.bounds.height, height: self.bounds.width))
        rotationView.transform = translateRotateFlip()
    }

    func translateRotateFlip() -> CGAffineTransform {

        var transform = CGAffineTransformIdentity

        // translate to new center
        transform = CGAffineTransformTranslate(transform, (self.bounds.width / 2)-(self.bounds.height / 2), (self.bounds.height / 2)-(self.bounds.width / 2))
        // rotate counterclockwise around center
        transform = CGAffineTransformRotate(transform, CGFloat(-M_PI_2))
        // flip vertically
        transform = CGAffineTransformScale(transform, -1, 1)

        return transform
    }
}

我最近的实现很可能位于这个github链接 https://github.com/suragch/MongolAppDevelopment-iOS/blob/master/Mongol%20App%20Componants/UIMongolTextView.swift.