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)
 }
}

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     
        }
    }
}  

你可以使用分类。设置左填充和右填充

UITextField+Padding.h

@interface UITextField (Padding)
@property (nonatomic, assign) CGFloat paddingValue;
@property (nonatomic, assign) CGFloat leftPadding;
@property (nonatomic, assign) CGFloat rightPadding;

//overwrite
-(CGRect)textRectForBounds:(CGRect)bounds;
-(CGRect)editingRectForBounds:(CGRect)bounds;
@end

UITextField+Padding.m

#import "UITextField+Padding.h"
#import <objc/runtime.h>

static char TAG_LeftPaddingKey;
static char TAG_RightPaddingKey;
static char TAG_Left_RightPaddingKey;

@implementation UITextField (Padding)

#pragma clang diagnostic push
#pragma clang diagnostic ignored "-Wobjc-protocol-method-implementation"
-(CGRect)textRectForBounds:(CGRect)bounds {

CGFloat offset_Left=0;
CGFloat offset_Right=0;
if (self.paddingValue>0) {
    offset_Left=self.paddingValue;
    offset_Right=offset_Left;
}else{
    if (self.leftPadding>0){
        offset_Left=self.leftPadding;
    }
    if (self.rightPadding>0){
        offset_Right=self.rightPadding;
    }
}

if (offset_Left>0||offset_Right>0) {
    return CGRectMake(bounds.origin.x+ offset_Left ,bounds.origin.y ,
                      bounds.size.width- (offset_Left+offset_Right), bounds.size.height-2 );
 }else{
    return bounds;
 }
}



-(CGRect)editingRectForBounds:(CGRect)bounds {
    return [self textRectForBounds:bounds];
}
#pragma clang diagnostic pop


#pragma maek -setter&&getter
- (CGFloat)paddingValue
{
    return [objc_getAssociatedObject(self,&TAG_Left_RightPaddingKey) floatValue];
}
-(void)setPaddingValue:(CGFloat)paddingValue
{
    objc_setAssociatedObject(self, &TAG_Left_RightPaddingKey, @(paddingValue), OBJC_ASSOCIATION_RETAIN_NONATOMIC);
}

-(CGFloat)leftPadding
{
    return [objc_getAssociatedObject(self,&TAG_LeftPaddingKey) floatValue];
}

-(void)setLeftPadding:(CGFloat)leftPadding
{
    objc_setAssociatedObject(self, &TAG_LeftPaddingKey, @(leftPadding), OBJC_ASSOCIATION_RETAIN_NONATOMIC);
}

-(CGFloat)rightPadding
{
    return [objc_getAssociatedObject(self,&TAG_RightPaddingKey) floatValue];
}

-(void)setRightPadding:(CGFloat)rightPadding
{
    objc_setAssociatedObject(self, &TAG_RightPaddingKey, @(rightPadding), OBJC_ASSOCIATION_RETAIN_NONATOMIC);
}

@end

你可以像这样设置填充 self.phoneNumTF.paddingValue f = 10.; 或 self.phoneNumTF.leftPadding f = 10.;

@Evil trout的回答很棒。我使用这种方法已经有一段时间了。它唯一缺少的是“处理大量文本字段”。我尝试了其他方法，但似乎不奏效。

子类化UITextField只是为了添加填充对我来说没有任何意义。因此，我迭代了所有UITextFields来添加填充。

-(void) addPaddingToAllTextFields:(UIView*)view {

    for(id currentView in [view subviews]){
        if([currentView isKindOfClass:[UITextField class]]) {
            // Change value of CGRectMake to fit ur need
            [currentView setLeftView:[[UIView alloc] initWithFrame:CGRectMake(0, 0, 10, 20)]];
            [currentView setLeftViewMode:UITextFieldViewModeAlways];
        }

        if([currentView respondsToSelector:@selector(subviews)]){
            [textfieldarray addObjectsFromArray:[self addPaddingToAllTextFields:currentView]];
        }
    }
}

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)
 }
}

textField.layer.borderWidth = 3;

将添加边框，这对我来说是填充。