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])

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])

Xcode 9.2 Swift 4

extension UITextField{
    @IBInspectable var placeHolderColor: UIColor? {
        get {
            return self.placeHolderColor
        }
        set {
            self.attributedPlaceholder = NSAttributedString(string:self.placeholder != nil ? self.placeholder! : "", attributes:[NSAttributedStringKey.foregroundColor: newValue!])
        }
    }
}

您可以使用带属性的字符串设置占位符文本。只需要把你想要的颜色传递给属性参数。

斯威夫特5:

let myTextField = UITextField(frame: CGRect(x: 0, y: 0, width: 200, height: 30))
myTextField.backgroundColor = .blue
myTextField.attributedPlaceholder = NSAttributedString(
    string: "Placeholder Text",
    attributes: [NSAttributedString.Key.foregroundColor: UIColor.white]
)

斯威夫特3:

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

年长的迅速:

myTextField.attributedPlaceholder = NSAttributedString(
    string: "Placeholder Text",
    attributes: [NSForegroundColorAttributeName: UIColor.white]
)

为迅速

创建UITextField扩展

extension UITextField{

    func setPlaceHolderColor(){
        self.attributedPlaceholder = NSAttributedString(string: self.placeholder!, attributes: [NSForegroundColorAttributeName : UIColor.white])
    }
}

如果你是从storyboard设置的。

extension UITextField{
    @IBInspectable var placeHolderColor: UIColor? {
        get {
            return self.placeHolderColor
        }
        set {
            self.attributedPlaceholder = NSAttributedString(string:self.placeholder != nil ? self.placeholder! : "", attributes:[NSAttributedString.Key.foregroundColor : newValue!])
        }
    }
}

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
    }
}