iOS 13 - UITextField with Placeholder getting app crash

Question

In iOS 13, I'm getting a crash when accessing the UITextField _placeholderLabel.textColor label key.

The key used to apply placeholder text color.

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

"NSGenericException" - reason: "Access to UITextField's _placeholderLabel ivar is prohibited. This is an application bug"

Answer 1

You can do it by using runtime:

add the following code to the bottom of placeholder setting

Ivar ivar =  class_getInstanceVariable([UITextField class], "_placeholderLabel");
UILabel *placeholderLabel = object_getIvar(textField, ivar);
placeholderLabel.textColor = [UIColor whiteColor];

At Xcode 11 beta2 ,this code is work ,but I don't know about GM version or official version.

The complete code:

• Objective-C Version

#import "ViewController.h"
#import <objc/runtime.h>

@interface ViewController ()

@end

@implementation ViewController

- (void)viewDidLoad {
    [super viewDidLoad];
    self.view.backgroundColor = [UIColor grayColor];
    self.title = @"UITextField Demo";

    UITextField *textField = [UITextField new];
    textField.frame = CGRectMake(0, 100, 300, 50);
    textField.placeholder = @"UITextField Demo";
    [self.view addSubview:textField];

    Ivar ivar =  class_getInstanceVariable([UITextField class], "_placeholderLabel");
    UILabel *placeholderLabel = object_getIvar(textField, ivar);

    placeholderLabel.textColor = [UIColor whiteColor];
}

@end

• Swift Version:

import UIKit

class ViewController: UIViewController {

    override func viewDidLoad() {
        let textField = UITextField()
        textField.frame = CGRect(x: 0, y: 100, width: 300, height: 50)
        textField.placeholder = "UITextField Demo"
        view.addSubview(textField)

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

2019/09/25 Update

The above implementation can solve the problem ,but it not be advocated.

The apps that use the private api maybe broken in the future.

Please use new api :

var attributedPlaceholder: NSAttributedString? { get set }

Discussion

This property is nil by default. If set, the placeholder string is drawn using system-defined color and the remaining style information (except the text color) of the attributed string. Assigning a new value to this property also replaces the value of the placeholder property with the same string data, albeit without any formatting information. Assigning a new value to this property does not affect any other style-related properties of the text field.

The complete code:

let textField = UITextField()
textField.frame = CGRect(x: 0, y: 100, width: 300, height: 50)
let placeholderString = NSAttributedString.init(string: "UITextField Demo", attributes: [NSAttributedString.Key.foregroundColor : UIColor.red])
textField.attributedPlaceholder = placeholderString
view.addSubview(textField)