如何子类 UITextField 并覆盖 drawPlaceholderInRect 以更改占位符颜色

Question

I have a 3 UITextField with placeholder text set. On one of the UITextField I want the placeholder text to be red.

Now after googling it seems the best way to do this is to subclass UITextField and override drawPlaceholderInRect .

How do I go about subclassing and overriding drawPlaceholderInRect ? I've not found any code examples or tutorials on this and I'm new to objective-c and iOS development so finding it tricky to work it out.

Answer:

Created a new objective-c class called CustomUITextFieldPlaceholder which subclassed UITextField . In CustomUITextFieldPlaceholder.m put the following code

 @implementation CustomUITextFieldPlaceholder

- (void)drawPlaceholderInRect:(CGRect)rect {
    // Set colour and font size of placeholder text
    [[UIColor redColor] setFill];
    [[self placeholder] drawInRect:rect withFont:[UIFont systemFontOfSize:12]];
}

@end

To implement the above in your project

#import "CustomUITextFieldPlaceholder.h"

and

IBOutlet CustomUITextFieldPlaceHolder *txtName;

Note: This works and I believe is correct practice, however I have not fully tested it. Hope this example helps others in my situation.

Edit:

Changed

[[UIColor redColor] setFill];

for

[[UIColor colorWithRed:255.0 green:0.0 blue:0.0 alpha:0.7] setFill];

So that I could set the opacity to 70% to mimic default placeholder.

Answer 1

To answer you specific question, this is how subclassing works:

// CustomTextField.h
@interface CustomTextField : UITextField {
}
@end

Here's how to override the method:

@implementation
- (CGRect)placeholderRectForBounds:(CGRect)bounds {
    return CGRectMake(x,y,width,height);
}
@end

However I don't think that's the method you want to override. I think this is what you're looking for:

@implementation
- (void)drawPlaceholderInRect:(CGRect)rect {
    // Your drawing code.
}
@end

Answer 2

[yourTextfield setValue:[UIColor colorWithRed:62.0/255.0f green:62.0/255.0f blue:62./255.0f alpha:1.0f]  forKeyPath:@"_placeholderLabel.textColor"];

I guess this would be helpful

Answer 3

Subclassing won't change the color. I have put forward a work around here.

UITextField placeholder font color white iOS 5?