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)
        }

如果你只需要左边空白，你可以试试这个:

UItextField *textField = [[UITextField alloc] initWithFrame:...];
UIView *leftView = [[UIView alloc] initWithFrame:CGRectMake(0, 0, 10, textField.frame.size.height)];
leftView.backgroundColor = textField.backgroundColor;
textField.leftView = leftView;
textField.leftViewMode = UITextFieldViewModeAlways;

这对我很管用。我希望这能有所帮助。

在从UITextField派生的类中，至少重写以下两个方法:

- (CGRect)textRectForBounds:(CGRect)bounds;
- (CGRect)editingRectForBounds:(CGRect)bounds;

如果你没有额外的内容，它可能就像这样简单:

return CGRectInset(bounds , 10, 10);

UITextField提供了几个可以覆盖的定位方法。

我想我可以提供一个快速解决方案

import UIKit

class TextField: UITextField {
    let inset: CGFloat = 10

    // placeholder position
    override func textRectForBounds(bounds: CGRect) -> CGRect {
        return CGRectInset(bounds , inset , inset)
    }

    // text position
    override func editingRectForBounds(bounds: CGRect) -> CGRect {
        return CGRectInset(bounds , inset , inset)
    }

    override func placeholderRectForBounds(bounds: CGRect) -> CGRect {
        return CGRectInset(bounds, inset, inset) 
    }
}

斯威夫特 3+

import UIKit

class TextField: UITextField {
    let inset: CGFloat = 10

    // placeholder position
    override func textRect(forBounds: CGRect) -> CGRect {
        return forBounds.insetBy(dx: self.inset , dy: self.inset)
    }

    // text position
    override func editingRect(forBounds: CGRect) -> CGRect {
        return forBounds.insetBy(dx: self.inset , dy: self.inset)
    }

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

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;