Question

This morning I was looking over some old code I found somewhere (and used in an app) that hacks a UIAlertView in order to get one string of input from the user. It’s overkill for the purpose and looks rather silly but I’ve never seen a simpler way. I then came up with the following approach, which seems to work (iPad 5.1.1 and simulator).

My question is a bit open-ended but, essentially, are there conditions under which this breaks as a strategy: create an off-screen text field with an accessory view, put a proxy text field in the accessory view, and forward various property settings to the proxy?

PMKeyboardTextField.h:

#import <UIKit/UIKit.h>

@interface PMKeyboardTextField : UITextField
- (id)initWithPrompt:(NSString *)prompt;
@end

PMKeyboardTextField.m:

#import "PMKeyboardTextField.h"

@interface PMKeyboardTextField ()
@property (nonatomic, strong) UITextField *inputField;
@end

@implementation PMKeyboardTextField
@synthesize inputField = _inputField;

- (id)initWithPrompt:(NSString *)prompt {
    self = [super initWithFrame:CGRectMake(-1, -1, 1, 1)];
    if (self) {
        UIView *accessory =  [[UIView alloc] initWithFrame:CGRectMake(0, 0, 300, 72)];
        [accessory setBackgroundColor:[UIColor colorWithRed:0.8 green:0.8 blue:0.8 alpha:0.8]];

        UILabel *getLabel = [[UILabel alloc] initWithFrame:CGRectMake(8, 8, 284, 21)];
        [getLabel setBackgroundColor:[UIColor clearColor]];
        getLabel.text = prompt;
        [accessory addSubview:getLabel];

        self.inputField = [[UITextField alloc] initWithFrame:CGRectMake(18, 37, 264, 31)];
        [accessory addSubview:self.inputField];

        self.inputAccessoryView = accessory;
        [[NSNotificationCenter defaultCenter] addObserver:self
                                                 selector:@selector(keyboardDidShow)
                                                     name:UIKeyboardDidShowNotification
                                                   object:nil];
    }
    return self;
}

- (void)keyboardDidShow {
    [self.inputField becomeFirstResponder];
}

- (id<UITextFieldDelegate>)delegate {
    return self.inputField.delegate;
}

- (void)setDelegate:(id<UITextFieldDelegate>)delegate {
    self.inputField.delegate = delegate;
}

- (void)dealloc {
    [[NSNotificationCenter defaultCenter] removeObserver:self];
}
@end

Answer 1

As much as I like this idea for its ability to avoid the excess clutter of an alert view or the need to reposition on-screen views, the fatal flaw was pointed out to me in another forum: some people use external keyboards!