我已经遇到过这个问题了。在我的情况下，以下代码是正确的。

Objective - C

[textField setValue:[UIColor whiteColor] forKeyPath:@"_placeholderLabel.textColor"];

Swift 4。X

tf_mobile.setValue(UIColor.white, forKeyPath: "_placeholderLabel.textColor")

适用于iOS 13 Swift Code

tf_mobile.attributedPlaceholder = NSAttributedString(string:"PlaceHolder Text", attributes: [NSAttributedString.Key.foregroundColor: UIColor.red])

你也可以在iOS 13中使用下面的代码

let iVar = class_getInstanceVariable(UITextField.self, "_placeholderLabel")!
let placeholderLabel = object_getIvar(tf_mobile, iVar) as! UILabel
placeholderLabel.textColor = .red

霍普，这个也许能帮到你。

在iOS7中处理垂直和水平对齐以及占位符的颜色。drawwinrect和drawAtPoint不再使用当前上下文的fillColor。

https://developer.apple.com/library/ios/documentation/StringsTextFonts/Conceptual/TextAndWebiPhoneOS/CustomTextProcessing/CustomTextProcessing.html

卷-C

@interface CustomPlaceHolderTextColorTextField : UITextField

@end


@implementation CustomPlaceHolderTextColorTextField : UITextField


-(void) drawPlaceholderInRect:(CGRect)rect  {
    if (self.placeholder) {
        // color of placeholder text
        UIColor *placeHolderTextColor = [UIColor redColor];

        CGSize drawSize = [self.placeholder sizeWithAttributes:[NSDictionary dictionaryWithObject:self.font forKey:NSFontAttributeName]];
        CGRect drawRect = rect;

        // verticially align text
        drawRect.origin.y = (rect.size.height - drawSize.height) * 0.5;

        // set alignment
        NSMutableParagraphStyle *paragraphStyle = [[NSMutableParagraphStyle alloc] init];
        paragraphStyle.alignment = self.textAlignment;

        // dictionary of attributes, font, paragraphstyle, and color
        NSDictionary *drawAttributes = @{NSFontAttributeName: self.font,
                                     NSParagraphStyleAttributeName : paragraphStyle,
                                     NSForegroundColorAttributeName : placeHolderTextColor};


        // draw
        [self.placeholder drawInRect:drawRect withAttributes:drawAttributes];
    }
}

@end

类别增值。可以优化检查有效的颜色变化。

#import <UIKit/UIKit.h>

@interface UITextField (OPConvenience)

@property (strong, nonatomic) UIColor* placeholderColor;

@end

#import "UITextField+OPConvenience.h"

@implementation UITextField (OPConvenience)

- (void) setPlaceholderColor: (UIColor*) color {
    if (color) {
        NSMutableAttributedString* attrString = [self.attributedPlaceholder mutableCopy];
        [attrString setAttributes: @{NSForegroundColorAttributeName: color} range: NSMakeRange(0,  attrString.length)];
        self.attributedPlaceholder =  attrString;
    }
}

- (UIColor*) placeholderColor {
    return [self.attributedPlaceholder attribute: NSForegroundColorAttributeName atIndex: 0 effectiveRange: NULL];
}

@end

我是xcode的新手，我找到了一种方法来达到同样的效果。

我放置了一个uilabel的位置占位符与所需的格式和隐藏它

- (void)textFieldDidBeginEditing:(UITextField *)textField
{
    switch (textField.tag)
    {
        case 0:
            lblUserName.hidden=YES;
            break;

        case 1:
            lblPassword.hidden=YES;
            break;
 
        default:
            break;
    }
}

我同意这是一个工作，而不是一个真正的解决方案，但效果是一样的，从这个链接

注:仍然适用于iOS 7:|

简单无痛，对一些人来说可能是一个简单的选择。

_placeholderLabel.textColor

不建议制作，Apple可能会拒绝您的提交。

Xamarin的。iOS开发者，我从这个文档中找到的 https://developer.xamarin.com/api/type/Foundation.NSAttributedString/

textField.AttributedPlaceholder = new NSAttributedString ("Hello, world",new UIStringAttributes () { ForegroundColor =  UIColor.Red });