将 selectionRects(for:) 与 UITextField 子类一起使用

Question

我有一个 UITextField 子类，我在其中覆盖左视图、文本和插入符号的绘图矩形。这是使用 leftViewRect(forBounds:)、leftViewRect(forBounds:)、caretRect(for:) 等完成的。一切都按预期进行。

问题是因为我在 caretRect(for:) 中将绘图矩形（向上）移动了 -2 点，所选文本的绘图矩形比应有的低了 2 点。我尝试覆盖 selectionRects(for:)，但 UITextSelectionRect 的 rect 是一个只获取属性。实现此目标的正确方法是什么？

代码

public override func selectionRects(for range: UITextRange) -> [UITextSelectionRect] {
    super.selectionRects(for: range).map {
        var selectionRect = [=10=]
        selectionRect.rect.origin.y -= 2 // Left side of mutating operator isn't mutable: 'rect' is a get-only property
        return selectionRect
    }
}

Answer 1

根据 rmaddy 的评论和，我通过子类化 UITextSelectionRect 并传入来自 super.selectionRects(for: range) 的映射值和修改后的 rect 解决了这个问题。这就是我的目标：

public final class MyUITextField: UITextField {
    public override func selectionRects(for range: UITextRange) -> [UITextSelectionRect] {
        super.selectionRects(for: range).map {
            MyTextSelectionRect(
                rect: CGRect(x: [=10=].rect.origin.x, y: [=10=].rect.origin.y - 2, width: [=10=].rect.width, height: [=10=].rect.height),
                writingDirection: [=10=].writingDirection,
                containsStart: [=10=].containsStart,
                containsEnd: [=10=].containsEnd,
                isVertical: [=10=].isVertical
            )
        }
    }

    //...
}

public final class MyTextSelectionRect: UITextSelectionRect {
    public override var rect: CGRect { _rect }
    public override var writingDirection: NSWritingDirection { _writingDirection }
    public override var containsStart: Bool { _containsStart }
    public override var containsEnd: Bool { _containsEnd }
    public override var isVertical: Bool { _isVertical }

    private let _rect: CGRect
    private let _writingDirection: NSWritingDirection
    private let _containsStart: Bool
    private let _containsEnd: Bool
    private let _isVertical: Bool

    public init(
        rect: CGRect,
        writingDirection: NSWritingDirection,
        containsStart: Bool,
        containsEnd: Bool,
        isVertical: Bool
    ) {
        _rect = rect
        _writingDirection = writingDirection
        _containsStart = containsStart
        _containsEnd = containsEnd
        _isVertical = isVertical
    }
}

将 selectionRects(for:) 与 UITextField 子类一起使用

Using selectionRects(for:) with UITextField subclass

selection

uitextfield

uikit

swift