Swift 2.0版本:

let paddingView: UIView = UIView(frame: CGRectMake(0, 0, 5, 20))
textField.leftView = paddingView
textField.leftViewMode = UITextFieldViewMode.Always;

基于Evil Trout的回答，你可能想要创建一个类别，使它更容易在多个应用程序中使用。

头文件:

@interface UITextField (PaddingText)

-(void) setLeftPadding:(int) paddingValue;

-(void) setRightPadding:(int) paddingValue;
@end

实现文件:

#import "UITextField+PaddingText.h"

@implementation UITextField (PaddingText)

-(void) setLeftPadding:(int) paddingValue
{
    UIView *paddingView = [[UIView alloc] initWithFrame:CGRectMake(0, 0, paddingValue, self.frame.size.height)];
    self.leftView = paddingView;
    self.leftViewMode = UITextFieldViewModeAlways;
}

-(void) setRightPadding:(int) paddingValue
{
    UIView *paddingView = [[UIView alloc] initWithFrame:CGRectMake(0, 0, paddingValue, self.frame.size.height)];
    self.rightView = paddingView;
    self.rightViewMode = UITextFieldViewModeAlways;
}

@end

使用的例子

#import "UITextField+PaddingText.h"

[self.YourTextField setLeftPadding:20.0f];

希望这对你们有所帮助

干杯

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     
        }
    }
}  

我是基于Nate的解决方案，但后来我发现，这导致问题，当你使用leftView/rightView属性，所以它更好地调优超级的实现，因为它将左/右视图的考虑。

- (CGRect)textRectForBounds:(CGRect)bounds {
    CGRect ret = [super textRectForBounds:bounds];
    ret.origin.x = ret.origin.x + 5;
    ret.size.width = ret.size.width - 10;
    return ret;
}

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

Swift 3解决方案

class CustomTextField: UITextField {

 override func textRect(forBounds bounds: CGRect) -> CGRect {
  return CGRect(x: bounds.origin.x + 10, y: bounds.origin.y + 8, width: bounds.size.width - 20, height: bounds.size.height - 16)
 }

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

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。