对于swift 4.2及以上版本，你可以这样做:

textField.attributedPlaceholder = NSAttributedString(string: "Placeholder Text", attributes: [NSAttributedString.Key.foregroundColor: UIColor.white])

就我而言，我做了以下事情:

extension UITextField {
    @IBInspectable var placeHolderColor: UIColor? {
        get {
            if let color = self.attributedPlaceholder?.attribute(.foregroundColor, at: 0, effectiveRange: nil) as? UIColor {
                return color
            }
            return nil
        }
        set (setOptionalColor) {
            if let setColor = setOptionalColor {
                let string = self.placeholder ?? ""
                self.attributedPlaceholder = NSAttributedString(string: string , attributes:[NSAttributedString.Key.foregroundColor: setColor])
            }
        }
    }
}

Swift 3(可能是2)，你可以覆盖didSet占位符在UITextField子类上应用属性，这样:

override var placeholder: String? {

    didSet {
        guard let tmpText = placeholder else {
            self.attributedPlaceholder = NSAttributedString(string: "")
            return
        }

        let textRange = NSMakeRange(0, tmpText.characters.count)
        let attributedText = NSMutableAttributedString(string: tmpText)
        attributedText.addAttribute(NSForegroundColorAttributeName , value:UIColor(white:147.0/255.0, alpha:1.0), range: textRange)

        self.attributedPlaceholder = attributedText
    }
}

在Swift 3.0中，使用

let color = UIColor.lightText
textField.attributedPlaceholder = NSAttributedString(string: textField.placeholder, attributes: [NSForegroundColorAttributeName : color])

在Siwft 5.0 +使用

let color = UIColor.lightText
let placeholder = textField.placeholder ?? "" //There should be a placeholder set in storyboard or elsewhere string or pass empty
textField.attributedPlaceholder = NSAttributedString(string: placeholder, attributes: [NSAttributedString.Key.foregroundColor : color])

对于Swift 3和3.1，这工作得非常好:

passField.attributedPlaceholder = NSAttributedString(string: "password", attributes: [NSForegroundColorAttributeName: UIColor.white])

crubio对Swift 4的答案更新

选择UITextField并打开右边的标识检查器:

单击加号按钮并添加一个新的运行时属性:placeholderLabel。textColor(代替_placeholderLabel.textColor)

使用颜色作为类型并选择颜色。

如果您运行您的项目，您将看到这些更改。