为UITextField添加填充的一个好方法是子类化UITextField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 = UIEdgeInsetsMake(0, 0, 0, 0);
    }
    return self;
}

-(id)initWithCoder:(NSCoder *)aDecoder{
    self = [super initWithCoder:aDecoder];
    if(self){
        self.edgeInsets = UIEdgeInsetsMake(0, 0, 0, 0);
    }
    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

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;

斯威夫特

    // adjust place holder text
    let paddingView = UIView(frame: CGRectMake(0, 0, 10, usernameOrEmailField.frame.height))
    usernameOrEmailField.leftView = paddingView
    usernameOrEmailField.leftViewMode = UITextFieldViewMode.Always

Swift 4.2版本:

import UIKit

class InsetTextField: UITextField {

  let inset: CGFloat = 10

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


  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)
  }

}

我通常尽量避免子类化，但如果你已经:

// add a property 
@property (nonatomic) UIEdgeInsets edgeInsets;

// and override:

- (CGRect)textRectForBounds:(CGRect)bounds
{
    return [super textRectForBounds:UIEdgeInsetsInsetRect(bounds, self.edgeInsets)];
}

- (CGRect)editingRectForBounds:(CGRect)bounds
{
    return [super editingRectForBounds:UIEdgeInsetsInsetRect(bounds, self.edgeInsets)];
}

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。