Objective c 在Ios中创建只有底线的文本字段

可以在Ios中创建一个文本字段，该字段只显示底部边框线，而不显示上部和侧面线条。如果是，我如何实现这一点

是的，这是可能的。以下是如何做到这一点：

CALayer *border = [CALayer layer];
CGFloat borderWidth = 2;
border.borderColor = [UIColor darkGrayColor].CGColor;
border.frame = CGRectMake(0, textField.frame.size.height - borderWidth, textField.frame.size.width, textField.frame.size.height);
border.borderWidth = borderWidth;
[textField.layer addSublayer:border];
textField.layer.masksToBounds = YES;

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希望这有帮助

Swift中用户4645956的解决方案

private func addBottomLineToTextField(textField : UITextField) {
    let border = CALayer()
    let borderWidth = CGFloat(1.0)
    border.borderColor = UIColor.whiteColor().CGColor
    border.frame = CGRectMake(0, textField.frame.size.height - borderWidth, textField.frame.size.width, textField.frame.size.height)
    border.borderWidth = borderWidth
    textField.layer.addSublayer(border)
    textField.layer.masksToBounds = true
}

用法：

    self.addBottomLineToTextField(usernameTextField)
    self.addBottomLineToTextField(passwordTextField)

斯威夫特：

可以这样称呼：

yourtextFieldName.useUnderline()

---

只需在Ios中使用CALayer到文本字段，并仅使用底线即可

CALayer *bottomBorder = [CALayer layer];
bottomBorder.frame = CGRectMake(0.0f, self.passwordField.frame.size.height - 1, self.passwordField.frame.size.width, 1.0f);
bottomBorder.backgroundColor = [UIColor blackColor].CGColor;
[self.passwordField.layer addSublayer:bottomBorder];

更新为Swift 3.0

extension UITextField {    

    func useUnderline() {
        let border = CALayer()
        let borderWidth = CGFloat(1.0)
        border.borderColor = UIColor.lightGray.cgColor
        border.frame = CGRect(origin: CGPoint(x: 0,y :self.frame.size.height - borderWidth), size: CGSize(width: self.frame.size.width, height: self.frame.size.height))
        border.borderWidth = borderWidth
        self.layer.addSublayer(border)
        self.layer.masksToBounds = true
    }
}

---

谢谢，成功了。有什么方法可以将默认文本设置为文本框，但当我设置txtview.text.length时，它仍然显示0，即当我输入真实文本时，长度应该只增加。您可以输入

UILabel

。您可以解释更多关于它的信息吗？如果您给我发送指向新问题的链接，我将很高兴。这是linkborder.frame=CGRectMake（0，self.frame.size.height-borderWidth，self.frame.size.width，borderWidth）

extension UITextField {    

    func useUnderline() {
        let border = CALayer()
        let borderWidth = CGFloat(1.0)
        border.borderColor = UIColor.lightGray.cgColor
        border.frame = CGRect(origin: CGPoint(x: 0,y :self.frame.size.height - borderWidth), size: CGSize(width: self.frame.size.width, height: self.frame.size.height))
        border.borderWidth = borderWidth
        self.layer.addSublayer(border)
        self.layer.masksToBounds = true
    }
}