我发现了罗伯托发布的选项。buratti是最快的解决方案，这里是Swift:

let leftView = UIView(frame: CGRect(x: 0, y: 0, width: 10, height: textField.frame.size.height))
leftView.backgroundColor = textField.backgroundColor
textField.leftView = leftView
textField.leftViewMode = UITextField.ViewMode.always

对于那些正在寻找更简单解决方案的人来说。

在UIView中添加UITextField。为了模拟文本框周围的插入，我保持左10像素，宽度比视图小20像素。对于文本框周围的圆角边框，请使用视图的边框

viewBG.layer.cornerRadius = 8.0;
viewBG.layer.borderColor = [UIColor darkGrayColor].CGColor;
viewBG.layer.borderWidth = 1.0;

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
    }()

}

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;
}

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)
    }
}

抛出另一个不需要子类化的解决方案:

UITextField *txtField = [UITextField new];
txtField.borderStyle = UITextBorderStyleRoundedRect;

// grab BG layer
CALayer *bgLayer = txtField.layer.sublayers.lastObject;
bgLayer.opacity = 0.f;

// add new bg view
UIView *bgView = [UIView new];
bgView.backgroundColor = [UIColor whiteColor];
bgView.autoresizingMask = UIViewAutoresizingFlexibleHeight | UIViewAutoresizingFlexibleWidth;
bgView.userInteractionEnabled = NO;

[txtField addSubview: bgView];
[txtField sendSubviewToBack: bgView];

在iOS 7和iOS 8上测试。这两个工作。苹果仍然有可能修改UITextField的层层次结构，把事情搞砸了。