You'll need to create your own clear button image in this case. I would suggest taking a screenshot of the clear button and editing in photoshop.
You can take that image and create a UIButton with the image dimensions. From there you can set it as the UITextField's rightView. Like so:
UIButton *button = [UIButton buttonWithType:UIButtonTypeCustom];
[button setImage:[UIImage imageNamed:@"clear_button.png"] forState:UIControlStateNormal];
[button setFrame:CGRectMake(0.0f, 0.0f, 15.0f, 15.0f)]; // Required for iOS7
theTextField.rightView = button;
theTextField.rightViewMode = UITextFieldViewModeWhileEditing;
I typed that without syntax checking and what not so you'll want to check it out before running it. You'll also want to replace clear_button.png with whatever your image name is.
You'll also need to write your own method to clear the text field.
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