iOS:以编程方式在UITextView中上下左右移动光标 [英] iOS: Programmatically move cursor up, down, left and right in UITextView

问题描述

我使用以下代码将光标位置从UITextField的开头移至5个字符:

I use the following code to move the cursor position to 5 characters from the beginning of a UITextField:

 txtView.selectedRange = NSMakeRange(5, 0);

现在，如果我将光标放置在下图所示的任意位置，该如何向上，向下，向左和向右移动光标?

Now, if I have a cursor at an arbitrary position as shown in the image below, how can I move the cursor up, down, left and right?

推荐答案

左右应该比较容易.我想最棘手的部分是顶部和底部.我会尝试以下方法.

Left and right should be more or less easy. I guess the tricky part is top and bottom. I would try the following.

您可以使用caretRect方法找到光标的当前框架":

You can use caretRect method to find the current "frame" of the cursor:

if let cursorPosition = answerTextView.selectedTextRange?.start {
    let caretPositionRect = answerTextView.caretRect(for: cursorPosition)


}

然后向上或向下，我将使用该框架使用characterRange(at:)(或者可能是closestPosition(to:))在UITextView坐标中计算估计位置，例如向上:

Then to go up or down, I would use that frame to calculate estimated position in UITextView coordinates using characterRange(at:) (or maybe closestPosition(to:)), e.g. for up:

let yMiddle = caretPositionRect.origin.y + (caretPositionRect.height / 2)
let lineHeight = answerTextView.font?.lineHeight ?? caretPositionRect.height // default to caretPositionRect.height
// x does not change
let estimatedUpPoint = CGPoint(x: caretPositionRect.origin.x, y: yMiddle - lineHeight)
if let newSelection = answerTextView.characterRange(at: estimatedUpPoint) {
    // we have a new Range, lets just make sure it is not a selection
    newSelection.end = newSelection.start

    // and set it
    answerTextView.selectedTextRange = newSelection
} else {
    // I guess this happens if we go outside of the textView
}

我以前还没有真正做过，所以就把它当作应该为您服务的大致方向.

I haven't really done it before, so take this just as a general direction that should work for you.

所使用方法的文档位于此处.

Documentation to the methods used is here.

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