对于目标C:

UIColor *color = [UIColor colorWithRed:0.44 green:0.44 blue:0.44 alpha:1.0];
 emailTextField.attributedPlaceholder = [[NSAttributedString alloc] initWithString:@"Friend's Email" attributes:@{NSForegroundColorAttributeName: color}];

迅速:

emailTextField.attributedPlaceholder = NSAttributedString(string: "Friend's Email",
                             attributes: [NSAttributedString.Key.foregroundColor: UIColor.white])

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!])
        }
    }
}

对于Swift 3和3.1，这工作得非常好:

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

只要把下面的代码写进Appdelegate的didFinishLaunchingWithOptions方法，如果你想在Swift 4.2编写的整个应用程序中进行更改，使用这个方法

UILabel.appearance(whenContainedInInstancesOf: [UITextField.self]).textColor = UIColor.white

像这样创建UITextField扩展:

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!])
        }
    }
}

在你的故事板或。xib中。你会看到

在我的例子中，我必须将占位符设置为黑色。UITextField的名字是passwordText。下面的代码是在Swift 5中测试的，对我来说工作得很好。我也有一个现有的文本对应的占位符。

let placeholderColor = UIColor.black
passwordText.attributedPlaceholder = NSAttributedString(string: passwordText.placeholder!, attributes: [NSAttributedString.Key.foregroundColor : placeholderColor])