有了这个，我们可以在iOS中改变文本字段占位符文本的颜色

[self.userNameTxt setValue:[UIColor colorWithRed:41.0/255.0 green:91.0/255.0 blue:106.0/255.0 alpha:1.0] forKeyPath:@"_placeholderLabel.textColor"];

我需要保持占位符的对齐，这样亚当的答案对我来说就不够了。

为了解决这个问题，我使用了一个小的变化，我希望也能帮助到你们:

- (void) drawPlaceholderInRect:(CGRect)rect {
    //search field placeholder color
    UIColor* color = [UIColor whiteColor];

    [color setFill];
    [self.placeholder drawInRect:rect withFont:self.font lineBreakMode:UILineBreakModeTailTruncation alignment:self.textAlignment];
}

自从ios6在UIViews中引入了带属性字符串，就可以像这样为占位符文本分配颜色:

if ([textField respondsToSelector:@selector(setAttributedPlaceholder:)]) {
  UIColor *color = [UIColor blackColor];
  textField.attributedPlaceholder = [[NSAttributedString alloc] initWithString:placeholderText attributes:@{NSForegroundColorAttributeName: color}];
} else {
  NSLog(@"Cannot set placeholder text's color, because deployment target is earlier than iOS 6.0");
  // TODO: Add fall-back code to set placeholder color.
}

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

也许你想尝试这种方式，但苹果可能会警告你访问私有ivar:

[self.myTextField setValue:[UIColor darkGrayColor] 
                forKeyPath:@"_placeholderLabel.textColor"];

请注意 根据Martin Alléus的说法，iOS 7不再适用了。

迅速:

if let placeholder = yourTextField.placeholder {
    yourTextField.attributedPlaceholder = NSAttributedString(string:placeholder, 
        attributes: [NSForegroundColorAttributeName: UIColor.blackColor()])
}

在Swift 4.0中:

if let placeholder = yourTextField.placeholder {
    yourTextField.attributedPlaceholder = NSAttributedString(string:placeholder, 
        attributes: [NSAttributedStringKey.foregroundColor: UIColor.black])
}