如何将NSRange转换为Range<String。索引>在Swift?
我想使用以下UITextFieldDelegate方法:
func textField(textField: UITextField!,
shouldChangeCharactersInRange range: NSRange,
replacementString string: String!) -> Bool {
textField.text.stringByReplacingCharactersInRange(???, withString: string)
当前回答
extension StringProtocol where Index == String.Index {
func nsRange(of string: String) -> NSRange? {
guard let range = self.range(of: string) else { return nil }
return NSRange(range, in: self)
}
}
其他回答
在公认的答案中，我发现可选选项很麻烦。这适用于Swift 3，似乎对表情符号没有问题。
func textField(_ textField: UITextField,
shouldChangeCharactersIn range: NSRange,
replacementString string: String) -> Bool {
guard let value = textField.text else {return false} // there may be a reason for returning true in this case but I can't think of it
// now value is a String, not an optional String
let valueAfterChange = (value as NSString).replacingCharacters(in: range, with: string)
// valueAfterChange is a String, not an optional String
// now do whatever processing is required
return true // or false, as required
}
你需要使用Range<String。索引>而不是经典的NSRange。我这样做的方式(也许有一个更好的方式)是通过获取字符串的字符串。索引移动它与前进。
我不知道你要替换的范围是什么，但让我们假设你想替换前两个字符。
var start = textField.text.startIndex // Start at the string's start index
var end = advance(textField.text.startIndex, 2) // Take start index and advance 2 characters forward
var range: Range<String.Index> = Range<String.Index>(start: start,end: end)
textField.text.stringByReplacingCharactersInRange(range, withString: string)
Swift 5解决方案
简短的回答带有主要的扩展
extension NSRange {
public init(range: Range<String.Index>,
originalText: String) {
self.init(location: range.lowerBound.utf16Offset(in: originalText),
length: range.upperBound.utf16Offset(in: originalText) - range.lowerBound.utf16Offset(in: originalText))
}
}
详情请看这里
func textField(_ textField: UITextField, shouldChangeCharactersIn range: NSRange, replacementString string: String) -> Bool {
guard let current = textField.text, let r = Range(range, in: current) else {
return false
}
let text = current.replacingCharacters(in: r, with: string)
// ...
return true
}
func textField(textField: UITextField, shouldChangeCharactersInRange range: NSRange, replacementString string: String) -> Bool {
let strString = ((textField.text)! as NSString).stringByReplacingCharactersInRange(range, withString: string)
}
