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。

我子类化UITextField来处理这个，它支持左，上，右和底部的插入，以及清除按钮的定位。

MRDInsetTextField.h

#import <UIKit/UIKit.h>

@interface MRDInsetTextField : UITextField

@property (nonatomic, assign) CGRect inset;

@end

MRDInsetTextField.m

#import "MRDInsetTextField.h"

@implementation MRDInsetTextField

- (id)init
{
    self = [super init];
    if (self) {
        _inset = CGRectZero;
    }
    return self;
}

- (id)initWithCoder:(NSCoder *)aDecoder
{
    self = [super initWithCoder:aDecoder];
    if (self) {
        _inset = CGRectZero;
    }
    return self;
}

- (id)initWithFrame:(CGRect)frame
{
    self = [super initWithFrame:frame];
    if (self) {
        _inset = CGRectZero;
    }
    return self;
}

- (void)setInset:(CGRect)inset {
    _inset = inset;

    [self setNeedsLayout];
}

- (CGRect)getRectForBounds:(CGRect)bounds withInset:(CGRect)inset {

    CGRect newRect = CGRectMake(
                         bounds.origin.x + inset.origin.x,
                         bounds.origin.y + inset.origin.y,
                         bounds.origin.x + bounds.size.width - inset.origin.x - inset.size.width,
                         bounds.origin.y + bounds.size.height - inset.origin.y - inset.size.height
                         );

    return newRect;
}

- (CGRect)textRectForBounds:(CGRect)bounds {
    return [self getRectForBounds:[super textRectForBounds:bounds] withInset:_inset];
}

- (CGRect)placeholderRectForBounds:(CGRect)bounds {
    return [self getRectForBounds:bounds withInset:_inset];
}

- (CGRect)editingRectForBounds:(CGRect)bounds {
    return [self getRectForBounds:[super editingRectForBounds:bounds] withInset:_inset];
}

- (CGRect)clearButtonRectForBounds:(CGRect)bounds {
    return CGRectOffset([super clearButtonRectForBounds:bounds], -_inset.size.width, _inset.origin.y/2 - _inset.size.height/2);
}

@end

*_someTextField*来自nib/storyboard视图，带有MRDInsetTextField自定义类的用法示例

[(MRDInsetTextField*)_someTextField setInset:CGRectMake(5, 0, 5, 0)]; // left, top, right, bottom inset

你可以通过设置leftView来设置UITextField的文本插入。

是这样的:

UITextField *yourTextField = [[UITextField alloc] init];
UIView *leftView = [[UIView alloc] initWithFrame:CGRectMake(0, 0, 5, 5)];
leftView.backgroundColor = [UIColor clearColor];
yourTextField.leftViewMode = UITextFieldViewModeAlways;
yourTextField.leftView = leftView;

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;

下面是在Swift 3中编写的相同子类UITextField。它与之前的Swift版本有很大的不同，正如你将看到的:

import UIKit

class MyTextField: UITextField
    {
    let inset: CGFloat = 10

    // 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)
        }

    override func placeholderRect(forBounds bounds: CGRect) -> CGRect
        {
        return bounds.insetBy(dx: inset, dy: inset)
        }
    }

顺便说一句，如果你只想控制一侧的插入，你也可以像下面这样做。如果你把一个图像放在UITextField的顶部，但你想让它在用户看来是在文本框中，那么这个只调整左边插图的特殊例子就很方便了:

    override func editingRect(forBounds bounds: CGRect) -> CGRect
        {
        return CGRect.init(x: bounds.origin.x + inset, y: bounds.origin.y, width: bounds.width - inset, height: bounds.height)
        }

解决方案:实际有效且适用于所有情况的解决方案:

应该使用offsetBy而不是insetBy。 也应该调用超函数来获取原始的Rect。 Bounds故障。你需要抵消原来的X, Y，边界有X, Y为零。 原始的x, y可以是非零，例如当设置UITextField的leftView时。

示例:

override func textRect(forBounds bounds: CGRect) -> CGRect {
    return super.textRect(forBounds: bounds).offsetBy(dx: 0.0, dy: 4)
}


override func editingRect(forBounds bounds: CGRect) -> CGRect {
    return super.editingRect(forBounds: bounds).offsetBy(dx: 0.0, dy: 4)
}