ios - 如何在 UITextField leftView 图像上获得左填充？

Question

我正在将 UIImageView 设置为 UITextField 上的 leftView，如下所示:

UIImageView *envelopeView = [[UIImageView alloc] initWithFrame:CGRectMake(0, 0, self.height*.1, self.height*.1)];
envelopeView.image = [UIImage imageNamed:@"envelope.png"];
envelopeView.contentMode = UIViewContentModeScaleAspectFit;
envelopeView.bounds = CGRectInset(envelopeView.frame, 15, 10);
self.emailAddress.leftView = envelopeView;
self.emailAddress.leftViewMode = UITextFieldViewModeAlways;

这让我得到以下信息:

如您所见，即使我尝试设置插图，图像的左侧尺寸也会一直延伸到按钮的左边缘。我怎样才能把这个信封移进去，让它四面都有填充物？

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更新:我尝试了像这样更改 UIImageView 框架的建议答案，但信封仍然排在 UITextField 边界的左侧:

CGFloat padding = 20;
UIImageView *envelopeView = [[UIImageView alloc] initWithFrame:CGRectMake(3*padding, padding, self.height*.1-padding, self.height*.1-padding)];

Answer 1

对于 Swift 3 用户

这是对我有用的:

extension UITextField {

 /// set icon of 20x20 with left padding of 8px 
 func setLeftIcon(_ icon: UIImage) {

    let padding = 8
    let size = 20

    let outerView = UIView(frame: CGRect(x: 0, y: 0, width: size+padding, height: size) )
    let iconView  = UIImageView(frame: CGRect(x: padding, y: 0, width: size, height: size))
    iconView.image = icon
    outerView.addSubview(iconView)

    leftView = outerView
    leftViewMode = .always  
  }
}

测试:

txOrigin.setLeftIcon(icon_location)

结果: