Ios – how to move cursor in UITextField after setting its value

iosnsnumberformatterselectedtextuitextfield

can anybody help me with this: i need to implement UITextField for input number. This number should always be in decimal format with 4 places e.g. 12.3456 or 12.3400.
So I created NSNumberFormatter that helps me with decimal places.

I am setting the UITextField value in

-(BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string
method.
I proccess input, use formatter and finally call [textField setText: myFormattedValue];

This works fine but this call also moves the cursor to the end of my field. That is unwanted. E.g. I have 12.3400 in my field and the cursor is located on the very beginning and user types number 1. The result value is 112.3400 but cursor is moved at the end. I want to end with cursor when the user expects (just after the number 1 recently added). There are some topics about setting cursor in TextView but this is UITextField. I also tried to catch selectedTextRange of the field, which saves the cursor position properly but after setText method call, this automatically changes and the origin UITextRange is lost (changed to current). hopefully my explanation is clear.

Please, help me with this. thank you very much.

EDIT : Finally, i decided to switch the functionality to changing the format after whole editing and works good enough. I have done it by adding a selector forControlEvents:UIControlEventEditingDidEnd.

Best Answer

After the UITextField.text property is changed, any previous references to UITextPosition or UITextRange objects that were associated with the old text will be set to nil after you set the text property. You need to store what the text offset will be after the manipulation will be BEFORE you set the text property.

This worked for me (note, you do have to test whether cursorOffset is < textField.text.length if you remove any characters from t in the example below):

- (BOOL) textField:(UITextField *) textField shouldChangeCharactersInRange:(NSRange) range replacementString:(NSString *) string

{
    UITextPosition *beginning = textField.beginningOfDocument;
    UITextPosition *start = [textField positionFromPosition:beginning offset:range.location];
    UITextPosition *end = [textField positionFromPosition:start offset:range.length];
    UITextRange *textRange = [textField textRangeFromPosition:start toPosition:end];

    // this will be the new cursor location after insert/paste/typing
    NSInteger cursorOffset = [textField offsetFromPosition:beginning toPosition:start] + string.length; 

    // now apply the text changes that were typed or pasted in to the text field
    [textField replaceRange:textRange withText:string];

    // now go modify the text in interesting ways doing our post processing of what was typed...
    NSMutableString *t = [textField.text mutableCopy];
    t = [t upperCaseString];
    // ... etc

    // now update the text field and reposition the cursor afterwards
    textField.text = t;
    UITextPosition *newCursorPosition = [textField positionFromPosition:textField.beginningOfDocument offset:cursorOffset];
    UITextRange *newSelectedRange = [textField textRangeFromPosition:newCursorPosition toPosition:newCursorPosition];
    [textField setSelectedTextRange:newSelectedRange];

    return NO;
}

Related Solutions

Ios – How to make a UITextField move up when the keyboard is present – on starting to edit

You will only need a ScrollView if the contents you have now do not fit in the iPhone screen. (If you are adding the ScrollView as the superview of the components just to make the TextField scroll up when keyboard comes up, then it's not needed.)
The standard way to prevent the TextFields from being covered by the keyboard is to move the view up/down whenever the keyboard is shown.

Here is some sample code:

#define kOFFSET_FOR_KEYBOARD 80.0

-(void)keyboardWillShow {
    // Animate the current view out of the way
    if (self.view.frame.origin.y >= 0)
    {
        [self setViewMovedUp:YES];
    }
    else if (self.view.frame.origin.y < 0)
    {
        [self setViewMovedUp:NO];
    }
}

-(void)keyboardWillHide {
    if (self.view.frame.origin.y >= 0)
    {
        [self setViewMovedUp:YES];
    }
    else if (self.view.frame.origin.y < 0)
    {
        [self setViewMovedUp:NO];
    }
}

-(void)textFieldDidBeginEditing:(UITextField *)sender
{
    if ([sender isEqual:mailTf])
    {
        //move the main view, so that the keyboard does not hide it.
        if  (self.view.frame.origin.y >= 0)
        {
            [self setViewMovedUp:YES];
        }
    }
}

//method to move the view up/down whenever the keyboard is shown/dismissed
-(void)setViewMovedUp:(BOOL)movedUp
{
    [UIView beginAnimations:nil context:NULL];
    [UIView setAnimationDuration:0.3]; // if you want to slide up the view

    CGRect rect = self.view.frame;
    if (movedUp)
    {
        // 1. move the view's origin up so that the text field that will be hidden come above the keyboard 
        // 2. increase the size of the view so that the area behind the keyboard is covered up.
        rect.origin.y -= kOFFSET_FOR_KEYBOARD;
        rect.size.height += kOFFSET_FOR_KEYBOARD;
    }
    else
    {
        // revert back to the normal state.
        rect.origin.y += kOFFSET_FOR_KEYBOARD;
        rect.size.height -= kOFFSET_FOR_KEYBOARD;
    }
    self.view.frame = rect;

    [UIView commitAnimations];
}


- (void)viewWillAppear:(BOOL)animated
{
    [super viewWillAppear:animated];
    // register for keyboard notifications
    [[NSNotificationCenter defaultCenter] addObserver:self
                                         selector:@selector(keyboardWillShow)
                                             name:UIKeyboardWillShowNotification
                                           object:nil];

    [[NSNotificationCenter defaultCenter] addObserver:self
                                         selector:@selector(keyboardWillHide)
                                             name:UIKeyboardWillHideNotification
                                           object:nil];
}

- (void)viewWillDisappear:(BOOL)animated
{
    [super viewWillDisappear:animated];
    // unregister for keyboard notifications while not visible.
    [[NSNotificationCenter defaultCenter] removeObserver:self
                                             name:UIKeyboardWillShowNotification
                                           object:nil];

    [[NSNotificationCenter defaultCenter] removeObserver:self
                                             name:UIKeyboardWillHideNotification
                                           object:nil];
}

Ios – Getting the cursor position of UITextField in ios

UITextField conforms to the UITextInput protocol which has methods for getting the current selection. But the methods are complicated. You need something like this:

- (BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string {
    if (textField.tag == 201) {
        UITextRange *selRange = textField.selectedTextRange;
        UITextPosition *selStartPos = selRange.start;
        NSInteger idx = [textField offsetFromPosition:textField.beginningOfDocument toPosition:selStartPos];

        [myclass selectTextForInput:textField atRange:NSMakeRange(idx, 0)];
    }
}

Best Answer

Related Solutions

Ios – How to make a UITextField move up when the keyboard is present – on starting to edit

Ios – Getting the cursor position of UITextField in ios

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