对于iOS13

+(void)ChangeplaceholderColor :(UITextField *)TxtFld andColor:(UIColor*)color { 
    NSMutableAttributedString *placeholderAttributedString = [[NSMutableAttributedString alloc] initWithAttributedString:TxtFld.attributedPlaceholder];
       [placeholderAttributedString addAttribute:NSForegroundColorAttributeName value:color range:NSMakeRange(0, [placeholderAttributedString length])];
       TxtFld.attributedPlaceholder = placeholderAttributedString;

}

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

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。

用于更改占位符文本颜色的Objective C代码。

首先导入这个objc/runtime类-

#进口< objc / >

然后替换文本字段名称- Ivar Ivar = class_getinstancvariable ([UITextField类]，"_placeholderLabel"); UILabel *placeholderLabel = object_getIvar(YourTxtField, ivar); placeholderLabel。textColor = [UIColor whiteColor];

它更多的是个性化你的textField，但无论如何，我将分享这段代码从另一个页面，使它更好一点:

import UIKit
extension UITextField {
func setBottomLine(borderColor: UIColor, fontColor: UIColor, placeHolderColor:UIColor, placeHolder: String) {
    self.borderStyle = UITextBorderStyle.none
    self.backgroundColor = UIColor.clear
    let borderLine = UIView()
    let height = 1.0
    borderLine.frame = CGRect(x: 0, y: Double(self.frame.height) - height, width: Double(self.frame.width), height: height)
    self.textColor = fontColor
    borderLine.backgroundColor = borderColor
    self.addSubview(borderLine)
    self.attributedPlaceholder = NSAttributedString(
        string: placeHolder,
        attributes: [NSAttributedStringKey.foregroundColor: placeHolderColor]
    )
  }
}

你可以这样使用它:

self.textField.setBottomLine(borderColor: lineColor, fontColor: fontColor, placeHolderColor: placeHolderColor, placeHolder: placeHolder)

知道你有一个UITextField连接到一个ViewController。

来源:http://codepany.com/blog/swift-3-custom-uitextfield-with-single-line-input/

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])