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     
        }
    }
}  

Objective C代码

MyTextField.h

#import <UIKit/UIKit.h>

@interface MyTextField : UITextField

@property (nonatomic) IBInspectable CGFloat padding;

@end

MyTextField.m

#import "MyTextField.h"

IB_DESIGNABLE
@implementation MyTextField

@synthesize padding;

-(CGRect)textRectForBounds:(CGRect)bounds{
    return CGRectInset(bounds, padding, padding);
}

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

@end

textField.layer.borderWidth = 3;

将添加边框，这对我来说是填充。

我发现使用不可编辑的UITextView并设置contenttoffset要容易得多

uiTextView.contentOffset = CGPointMake(8, 7);

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     
        }
    }
}  

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)
    }
}