斯威夫特

 class TextField: UITextField {

    let inset: CGFloat = 8

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

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

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
    }()

}

@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)
    }
}

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;

下面是在Swift 3中编写的相同子类UITextField。它与之前的Swift版本有很大的不同，正如你将看到的:

import UIKit

class MyTextField: UITextField
    {
    let inset: CGFloat = 10

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

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

    override func placeholderRect(forBounds bounds: CGRect) -> CGRect
        {
        return bounds.insetBy(dx: inset, dy: inset)
        }
    }

顺便说一句，如果你只想控制一侧的插入，你也可以像下面这样做。如果你把一个图像放在UITextField的顶部，但你想让它在用户看来是在文本框中，那么这个只调整左边插图的特殊例子就很方便了:

    override func editingRect(forBounds bounds: CGRect) -> CGRect
        {
        return CGRect.init(x: bounds.origin.x + inset, y: bounds.origin.y, width: bounds.width - inset, height: bounds.height)
        }

This is not as short as the other examples, but takes an entirely different approach to solving this problem. Note, the caret will still begin flush to the left edge but the text will be properly indented when typed/displayed. This works without subclassing if your looking for just a left margin and you are already using UITextFieldDelegate for your text fields. You need to set both the default text attributes and the typing attributes. You set the default text attributes when you create the text field. The typing attributes you need to set in the delegate. If you are also using a placeholder you will want to set that to the same margin as well. Putting it altogether you get something like this.

首先在UITextField类上创建一个类别。

//  UITextField+TextAttributes.h

#import <UIKit/UIKit.h>

@interface UITextField (TextAttributes)

- (void)setIndent:(CGFloat)indent;

@end


//  UITextField+TextAttributes.m
#import "UITextField+TextAttributes.h"

@implementation UITextField (TextAttributes)

- (void)setTextAttributes:(NSDictionary*)textAttributes indent:(CGFloat)indent
{
    if (!textAttributes) return;

    NSMutableParagraphStyle *paragraphStyle = [textAttributes objectForKey:NSParagraphStyleAttributeName];
    paragraphStyle.firstLineHeadIndent = indent;
    paragraphStyle.headIndent = indent;
}

- (void)setIndent:(CGFloat)indent
{
   [self setTextAttributes:self.defaultTextAttributes indent:indent];
   [self setTextAttributes:self.typingAttributes indent:indent];
}

@end

然后，如果您使用放置占位符，请确保使用带有属性的占位符设置相同的缩进。创建一个具有正确属性的默认属性字典，如下所示:

NSMutableParagraphStyle *paragraphStyle = [[NSMutableParagraphStyle alloc] init];
paragraphStyle.firstLineHeadIndent = 7;
paragraphStyle.headIndent = 7;
NSDictionary *placeholderAttributes = [NSDictionary dictionaryWithObjectsAndKeys: paragraphStyle, NSParagraphStyleAttributeName, nil];

然后，导入上述类别，每当你创建一个文本字段设置默认缩进，委托和使用默认占位符属性上面定义。例如:

UITextField *textField = [[UITextField alloc] init];
textField.indent = 7;
textField.delegate = self;
textField.attributedPlaceholder = [[NSAttributedString alloc] initWithString:@"Placeholder Text" attributes:placeholderAttributes];

最后，在委托中，实现textFieldDidBeginEditing方法，就像这样:

- (void)textFieldDidBeginEditing:(UITextField *)textField
{
    textField.indent = 7;
}