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

Swift 3的更新版本:

@IBDesignable
class FormTextField: UITextField {

    @IBInspectable var paddingLeft: CGFloat = 0
    @IBInspectable var paddingRight: CGFloat = 0

    override func textRect(forBounds bounds: CGRect) -> CGRect {
        return CGRect(x: bounds.origin.x + paddingLeft, y: bounds.origin.y, width: bounds.size.width - paddingLeft - paddingRight, height: bounds.size.height)
    }

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

布洛迪的方法对我很有效。我不得不在文本框上添加侧视图，并添加额外的填充。因此，通过实现自定义UIEdgeInsets属性到UITextField子类，我已经成功实现了任务。我将在所有项目中使用这个新子类。

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

创建一个文本域Custom

PaddingTextField.swift

import UIKit
class PaddingTextField: UITextField {

@IBInspectable var paddingLeft: CGFloat = 0
@IBInspectable var paddingRight: CGFloat = 0

override func textRectForBounds(bounds: CGRect) -> CGRect {
    return CGRectMake(bounds.origin.x + paddingLeft, bounds.origin.y,
        bounds.size.width - paddingLeft - paddingRight, bounds.size.height);
}

override func editingRectForBounds(bounds: CGRect) -> CGRect {
    return textRectForBounds(bounds)
}}

设置你的文本字段类是PaddingTextField和自定义你的填充，因为你想要 享受它

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     
        }
    }
}