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     
        }
    }
}  

@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]];
        }
    }
}

为UITextField添加填充的一个好方法是子类化并添加一个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 = UIEdgeInsetsZero;
    }
    return self;
}

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

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     
        }
    }
}  

就像这样子类UITextField (Swift版本):

import UIKit

class CustomTextField: UITextField {

    override func textRectForBounds(bounds: CGRect) -> CGRect {
       return CGRectInset(bounds, 25.0, 0)
    }

    override func editingRectForBounds(bounds: CGRect) -> CGRect {
       return self.textRectForBounds(bounds)
    }

}

这增加了25.0点的水平填充两边。

textField.layer.borderWidth = 3;

将添加边框，这对我来说是填充。