在从UITextField派生的类中，至少重写以下两个方法:

- (CGRect)textRectForBounds:(CGRect)bounds;
- (CGRect)editingRectForBounds:(CGRect)bounds;

如果你没有额外的内容，它可能就像这样简单:

return CGRectInset(bounds , 10, 10);

UITextField提供了几个可以覆盖的定位方法。

你必须子类化是荒谬的，因为UITextField已经实现了方法，就像@Adam Waite指出的那样。下面是一个快速扩展，它公开了一个工厂方法，也可以在我们的categories repo中使用:

private class InsetTextField: UITextField {
    var insets: UIEdgeInsets

    init(insets: UIEdgeInsets) {
        self.insets = insets
        super.init(frame: CGRectZero)
    }

    required init(coder aDecoder: NSCoder) {
        fatalError("not intended for use from a NIB")
    }

    // placeholder position
    override func textRectForBounds(bounds: CGRect) -> CGRect {
        return super.textRectForBounds(UIEdgeInsetsInsetRect(bounds, insets))
    }

    // text position
    override func editingRectForBounds(bounds: CGRect) -> CGRect {
        return super.editingRectForBounds(UIEdgeInsetsInsetRect(bounds, insets))
    }
}

extension UITextField {

    class func textFieldWithInsets(insets: UIEdgeInsets) -> UITextField {
        return InsetTextField(insets: insets)
    }

}

Swift 5版本的克里斯托弗的答案与额外的用法示例

import UIKit

private class InsetTextField: UITextField {
    var insets: UIEdgeInsets

    init(insets: UIEdgeInsets) {
        self.insets = insets
        super.init(frame: .zero)
    }

    required init(coder aDecoder: NSCoder) {
        fatalError("not intended for use from a NIB")
    }

    // placeholder position
    override func textRect(forBounds bounds: CGRect) -> CGRect {
         return super.textRect(forBounds: bounds.inset(by: insets))
    }
 
    // text position
    override func editingRect(forBounds bounds: CGRect) -> CGRect {
         return super.editingRect(forBounds: bounds.inset(by: insets))
    }
}

extension UITextField {

    class func textFieldWithInsets(insets: UIEdgeInsets) -> UITextField {
        return InsetTextField(insets: insets)
    }

}

用法:-

class ViewController: UIViewController {

  private let passwordTextField: UITextField = {

        let textField = UITextField.textFieldWithInsets(insets: UIEdgeInsets(top: 10, left: 15, bottom: 10, right: 15))
     // ---
   
        return textField
    }()

}

你可以通过设置leftView来设置UITextField的文本插入。

是这样的:

UITextField *yourTextField = [[UITextField alloc] init];
UIView *leftView = [[UIView alloc] initWithFrame:CGRectMake(0, 0, 5, 5)];
leftView.backgroundColor = [UIColor clearColor];
yourTextField.leftViewMode = UITextFieldViewModeAlways;
yourTextField.leftView = leftView;

重写-textRectForBounds:只会改变占位符文本的插入。要改变可编辑文本的插入，你还需要重写-editingRectForBounds:

// placeholder position
- (CGRect)textRectForBounds:(CGRect)bounds {
     return CGRectInset(bounds, 10, 10);
}

// text position
- (CGRect)editingRectForBounds:(CGRect)bounds {
     return CGRectInset(bounds, 10, 10);
}

@IBInspectable， @IBDesignable swift类怎么样?

@IBDesignable
class TextField: UITextField {
    @IBInspectable var insetX: CGFloat = 6 {
       didSet {
         layoutIfNeeded()
       }
    }
    @IBInspectable var insetY: CGFloat = 6 {
       didSet {
         layoutIfNeeded()
       }
    }

    // placeholder position
    override func textRectForBounds(bounds: CGRect) -> CGRect {
        return CGRectInset(bounds , insetX , insetY)
    }

    // text position
    override func editingRectForBounds(bounds: CGRect) -> CGRect {
        return CGRectInset(bounds , insetX , insetY)
    }
}

你会在你的故事板中看到这个。

更新- Swift 3

@IBDesignable
class TextField: UITextField {
    @IBInspectable var insetX: CGFloat = 0
    @IBInspectable var insetY: CGFloat = 0

    // placeholder position
    override func textRect(forBounds bounds: CGRect) -> CGRect {
        return bounds.insetBy(dx: insetX, dy: insetY)
    }

    // text position
    override func editingRect(forBounds bounds: CGRect) -> CGRect {
        return bounds.insetBy(dx: insetX, dy: insetY)
    }
}