UIKeyboardTypeDecimalPad with negative numbers - ios

Question

I'm working on an iOS app that requires the user to enter numbers into a UITextField using the keyboard type UIKeyboardTypeDecimalPad. However I just realized that there is no support for entering negative numbers, which is a requirement of the application.
Any ideas or thoughts on how I can accomplish this?

Answer 1

You can use a UIToolbar as an input accessory view for your UITextField and put a button with a "+/-" (plus/minus sign in it).
UIToolbar *toolbar = [[UIToolbar alloc]initWithFrame:CGRectMake(0, 0, self.view.bounds.size.width, 44)];
UIBarButtonItem *plusMinusBbi = [[UIBarButtonItem alloc]initWithTitle:#"+/-" style:UIBarButtonItemStylePlain target:self action:#selector(togglePositiveNegative:)];
toolbar.items = #[plusMinusBbi];
self.textField.inputAccessoryView = toolbar;

Answer 2

I don't believe that something like that is possible right now (since Apple hasn't implemented it yet). The only option would be to design your own keyboard or use a complete ASCII one.

Answer 3

func addToolbar() {
let toolbar = UIToolbar()
toolbar.sizeToFit()
let plusMinusButton = UIBarButtonItem(title: "+/-", style: .done, target: self, action: #selector(plusMinusAction))
plusMinusButton.tintColor = .black
plusMinusButton.width = UIScreen.main.bounds.width / 3
toolbar.items = [plusMinusButton]
toolbar.barTintColor = #colorLiteral(red: 0.7812563181, green: 0.8036255836, blue: 0.8297665119, alpha: 1)
toolbar.isTranslucent = false
myField.inputAccessoryView = toolbar
}
#objc func plusMinusAction() {
let text = myField.text ?? ""
if text.hasPrefix("-") {
myField.text = String(text.suffix(text.count - 1))
} else {
myField.text = "-\(text)"
}
}

Answer 4

From what I've found apple has yet to implement such a standard keyboard. However it is possible to add UIButtons to any keyboard window. this link should help, or similar tutorial this link should also help
Basically you register a NSNotificationListener to listen for the keyboard coming up. Grab the keyboards frame and add a UIButton to its view. The above link isn't quite what we want but its the right idea.
In appDelegate,
[[NSNotificationCenter defaultCenter] addObserver:self selector:#selector(keyboardDidShow:) name:UIKeyboardDidShowNotification object:nil];
- (void)keyboardDidShow:(NSNotification *)note
{
// Get the Very Top Window on the Display. That's where the Keyboard is.
NSInteger topWindow = [[[UIApplication sharedApplication] windows] count] - 1;
UIWindow *keyboard = [[[UIApplication sharedApplication] windows] objectAtIndex:topWindow];
// If the dot has not been created (first time the keyboard has been displayed) create it.
if (self.dot == nil)
{
self.dot = [UIButton buttonWithType:UIButtonTypeCustom];
// Make the dot a subview of the view containing the keyboard.
[keyboard addSubview:self.dot];
// Place the dot in the correct location on the keyboard.
[self.dot setFrame:CGRectMake(0, 427, 106, 53)];
// Set the overlay graphics. (Use TransDecimalDown.png and TransDecimalUp.png for the Alert Style Keyboard.
[self.dot setImage:[UIImage imageNamed:#"DecimalUp.png"] forState:UIControlStateNormal];
[self.dot setImage:[UIImage imageNamed:#"DecimalDown.png"] forState:UIControlStateHighlighted];
// Give the dot something to do when pressed.
[self.dot addTarget:self action:#selector(sendDecimal:) forControlEvents:UIControlEventTouchUpInside];
}
// Bring the dot to the front of the keyboard.
[keyboard bringSubviewToFront:self.dot];
}
- (void)sendDecimal:(id)sender {
// Post a notification that the dot has been pressed. Observing view controllers are then responsible for adding the actual decimal.
[[NSNotificationCenter defaultCenter] postNotificationName:#"DecimalPressed" object:nil];
// Play the Keyboard Click. If the user has these sound effects turned off, the decimal will still click. Sorry. :( (Also, doesn't seem to work on the simulator, no keyboard clicks seem to.)
AudioServicesPlaySystemSound(0x450);
}
sorry for the horrible code format but you get the idea :)

Answer 5

This clearly isn't my best answer.. but i'm unable to delete it since it is accepted.
may this code will help you:
if you want a negative number just use "-"
NSString *fieldString = [NSString stringWithFormat:#"%#",Textfield.text];
NSLog(#"%#",fString);
int fieldValue;
value = [fString intValue];
NSLog(#"%d",fieldValue);
this will work for decimal numbers
double fieldValue;
value = [fString doubleValue];
NSLog(#"%f",fieldValue);

Answer 6

To accomplish the task I came using '.inputAccessoryView' with the textfield
On viewDidLoad
self.textField.inputAccessoryView = [self accessoryViewForTextField:self.textField];
then
- (UIView *)accessoryViewForTextField:(UITextField *)textField{
UIView *view = [[UIView alloc] initWithFrame:CGRectMake(0, 0, self.view.frame.size.width, 44)];
view.backgroundColor = [UIColor lightGrayColor];
UIButton *minusButton = [UIButton buttonWithType:UIButtonTypeCustom];
UIButton *doneButton = [UIButton buttonWithType:UIButtonTypeCustom];
[minusButton setTitle:#"-" forState:UIControlStateNormal];
[doneButton setTitle:NSLocalizedString(#"Done", #"Done") forState:UIControlStateNormal];
minusButton.backgroundColor = [UIColor magentaColor];
doneButton.backgroundColor = [UIColor blueColor];
CGFloat buttonWidth = view.frame.size.width/3;
minusButton.frame = CGRectMake(0, 0, buttonWidth, 44);
doneButton.frame = CGRectMake(view.frame.size.width - buttonWidth, 0, buttonWidth, 44);
[minusButton addTarget:self action:#selector(minusTouchUpInside:) forControlEvents:UIControlEventTouchUpInside];
[doneButton addTarget:self action:#selector(doneTouchUpInside:) forControlEvents:UIControlEventTouchUpInside];
[view addSubview:minusButton];
[view addSubview:doneButton];
return view;
}
this will add a custom view just above the keyboard as a part of it
finally to get the 'minus'
#pragma mark - IBActions
- (IBAction)minusTouchUpInside:(id)sender
{
NSString *value = self.textField.text;
if (value.length > 0) {
NSString *firstCharacter = [value substringToIndex:1];
if ([firstCharacter isEqualToString:#"-"]){
self.textField.text = [value substringFromIndex:1];
}else{
self.textField.text = [NSString stringWithFormat:#"-%#", value];
}
}
}
- (IBAction)doneTouchUpInside:(id)sender
{
[self.textField resignFirstResponder];
}