限制UITextField 输入字数

最新推荐文章于 2024-05-22 16:10:35 发布

翻译最新推荐文章于 2024-05-22 16:10:35 发布 · 413 阅读

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#uitextfield #nsstring

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本文提供了Objective-C和Swift两种语言中UITextField输入字段长度限制的方法。通过计算当前文本长度加上新输入字符串长度减去替换字符长度来判断是否超出最大限制25个字符。

Objective-C

- (BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string {
    // Prevent crashing undo bug – see note below.
    if(range.length + range.location > textField.text.length)
    {
        return NO;
    }

    NSUInteger newLength = [textField.text length] + [string length] - range.length;
    return newLength <= 25;
}

Swift

func textField(textField: UITextField, shouldChangeCharactersInRange range: NSRange, replacementString string: String) -> Bool {

    let currentCharacterCount = textField.text?.characters.count ?? 0
    if (range.length + range.location > currentCharacterCount){
        return false
    }
    let newLength = currentCharacterCount + string.characters.count - range.length
    return newLength <= 25
}