只是UITextField的子类，像这样:

@implementation DFTextField


- (CGRect)textRectForBounds:(CGRect)bounds
{
    return CGRectInset(bounds, 10.0f, 0);
}

- (CGRect)editingRectForBounds:(CGRect)bounds
{
    return [self textRectForBounds:bounds];
}


@end

这增加了10点的水平填充两边。

如果有人正在寻找Swift 4.0版本，那么下面的扩展是工作。它有左填充和右填充UITextField。实际上它是IBInspectable用于storyboard配置。您可以直接从接口构建器/故事板设置该值。这是在Swift 4.0版本和Xcode 9.0的测试代码

请记住，如果你想在同一个UITextField上启用清除按钮，那么你必须保持右填充空白。

import UIKit

extension UITextField {

    @IBInspectable var paddingLeft: CGFloat {
        get {
            return leftView!.frame.size.width
        }
        set {
            let paddingView = UIView(frame: CGRect(x: 0, y: 0, width: newValue, height: frame.size.height))
            leftView = paddingView
            leftViewMode = .always
        }
    }

    @IBInspectable var paddingRight: CGFloat {
        get {
            return rightView!.frame.size.width
        }
        set {
            let paddingView = UIView(frame: CGRect(x: 0, y: 0, width: newValue, height: frame.size.height))
            rightView = paddingView
            rightViewMode = .always     
        }
    }
}  

为UITextField添加填充的一个好方法是子类化并添加一个edgeInsets属性。然后设置edgeInsets和UITextField将相应地绘制。对于自定义的leftView或rightView集，这也能正确地发挥作用。

OSTextField.h

#import <UIKit/UIKit.h>

@interface OSTextField : UITextField

@property (nonatomic, assign) UIEdgeInsets edgeInsets;

@end

OSTextField.m

#import "OSTextField.h"

@implementation OSTextField

- (id)initWithFrame:(CGRect)frame{
    self = [super initWithFrame:frame];
    if (self) {
        self.edgeInsets = UIEdgeInsetsZero;
    }
    return self;
}

-(id)initWithCoder:(NSCoder *)aDecoder{
    self = [super initWithCoder:aDecoder];
    if(self){
        self.edgeInsets = UIEdgeInsetsZero;
    }
    return self;
}

- (CGRect)textRectForBounds:(CGRect)bounds {
    return [super textRectForBounds:UIEdgeInsetsInsetRect(bounds, self.edgeInsets)];
}

- (CGRect)editingRectForBounds:(CGRect)bounds {
    return [super editingRectForBounds:UIEdgeInsetsInsetRect(bounds, self.edgeInsets)];
}

@end

到目前为止，我找到的最佳解决方案是分类。这就是我如何在左右两侧添加5点填充:

@implementation UITextField (Padding)

#pragma clang diagnostic push
#pragma clang diagnostic ignored "-Wobjc-protocol-method-implementation"
- (CGRect)textRectForBounds:(CGRect)bounds {
    return CGRectMake(bounds.origin.x + 5, bounds.origin.y,
                      bounds.size.width - 10, bounds.size.height);
}
- (CGRect)editingRectForBounds:(CGRect)bounds {
    return [self textRectForBounds:bounds];
}
#pragma clang diagnostic pop

@end

#pragma’s只是用来删除恼人的警告

textField.layer.borderWidth = 3;

将添加边框，这对我来说是填充。

我创建了这个类别实现，并将其添加到.m文件的顶部。

@implementation UITextField (custom)
    - (CGRect)textRectForBounds:(CGRect)bounds {
        return CGRectMake(bounds.origin.x + 10, bounds.origin.y + 8,
                          bounds.size.width - 20, bounds.size.height - 16);
    }
    - (CGRect)editingRectForBounds:(CGRect)bounds {
        return [self textRectForBounds:bounds];
    }
@end

根据彼得·布拉斯亚克提供的链接。这似乎比创建一个全新的子类更简单，也比添加额外的UIView更简单。不过，似乎缺少了一些东西，无法控制文本字段内的填充。

Swift 4解决方案:

class CustomTextField: UITextField {
    struct Constants {
        static let sidePadding: CGFloat = 10
        static let topPadding: CGFloat = 8
    }

    override func textRect(forBounds bounds: CGRect) -> CGRect {
        return CGRect(
            x: bounds.origin.x + Constants.sidePadding,
            y: bounds.origin.y + Constants.topPadding,
            width: bounds.size.width - Constants.sidePadding * 2,
            height: bounds.size.height - Constants.topPadding * 2
        )
    }

    override func editingRect(forBounds bounds: CGRect) -> CGRect {
        return self.textRect(forBounds: bounds)
    }
}