Question

我使用属性字符串格式化UITextView的单个字符串，只要单击按钮或移动选择器，它就会更新。但是，因为我使用attributedStringLine.append(attributedCharString) attributedString继续增长，而不是在更新UITextView时开始新的属性字符串。

下面的代码演示了问题的简化版本。

NSMutableAttributedString()对myArray中的字符串进行操作。 UITextView更改时会处理新字符串。这些内容位于array1, array2和array3。

import UIKit

var str = "Hello, playground"

let array1                      = ["7.0", "55.55", "1.0", "9.27"]
let array2                      = ["0", "10", "20", "30", "40"]
let array3                      = ["A", "B", "C", "D", "E", "F"]

var myArray                     = [""]
let attributedStringLine        = NSMutableAttributedString()
let numberOfRawStringCharacters = myArray.count


func appendTextString(i: Int){
    let rangeOfCharString       = (myArray[i] as NSString).range(of: myArray[i])
    let attributedCharString    = NSMutableAttributedString.init(string: myArray[i], attributes: [NSFontAttributeName: UIFont.systemFont(ofSize: 18.0, weight: UIFontWeightLight)])
    attributedCharString.addAttributes([NSForegroundColorAttributeName : UIColor.blue], range: rangeOfCharString)
    attributedStringLine.append(attributedCharString)
}


func makeText() {
    for i in 0..<myArray.count {
        appendTextString(i: i)
    }
}

var line = attributedStringLine.length

myArray.removeAll()
myArray                         = array1
myArray.count
makeText()
print(attributedStringLine)
line = attributedStringLine.length

myArray.removeAll()
myArray                         = array2
myArray.count
makeText()
attributedStringLine
line = attributedStringLine.length

myArray.removeAll()
myArray                         = array3
myArray.count
makeText()
attributedStringLine
line = attributedStringLine.length

每当UITextView发生变化时，如何从空的attributionString开始？

对于NSMutableString，替换或删除现有属性字符串范围内的字符似乎是唯一可用的替代方法。而且我很确定这不是Value of type 'NSMutableAttributedString' has no member 'removeAll'

的重复

Answer 1

由于您使用attributedStringLine声明了let，因此您可以在makeText开头删除其中的所有字符。

func makeText() {
    attributedStringLine.deleteCharacters(in: NSMakeRange(0, attributedStringLine.length))
    for i in 0..<myArray.count {
        appendTextString(i: i)
    }
}

或者您将其声明从let更改为var，然后在attributedStringLine = NSMutableAttributedString()开头使用makeText。

每当UITextView发生变化时，如何从空的attributionString开始？

1 个答案: