CODEWITHSUNDEEP
iosiphoneuitextfielduitextpositionuitextrange
Jeremy
Jeremy

Reputation: 849

Control cursor position in UITextField

I have a UITextField that I'm forcing formatting on by modifying the text inside the change notification handler. This works great (once I solved the reentrancy issues) but leaves me with one more nagging problem. If the user moves the cursor someplace other than the end of the string then my formatting change moves it to the end of the string. This means users cannot insert more than one character at a time into the middle of the text field. Is there a way to remember and then reset the cursor position in the UITextField?

Upvotes: 52

Views: 50734

Answers (7)

George Muntean
George Muntean

Reputation: 361

Useful to position at index (Swift 3)

private func setCursorPosition(input: UITextField, position: Int) {
    let position = input.position(from: input.beginningOfDocument, offset: position)!
    input.selectedTextRange = input.textRange(from: position, to: position)
}

Upvotes: 6

Pavel Alexeev
Pavel Alexeev

Reputation: 6081

Feel free to use this UITextField category to get and set cursor position:

@interface UITextField (CursorPosition)

@property (nonatomic) NSInteger cursorPosition;

@end

–

@implementation UITextField (CursorPosition)

- (NSInteger)cursorPosition
{
    UITextRange *selectedRange = self.selectedTextRange;
    UITextPosition *textPosition = selectedRange.start;
    return [self offsetFromPosition:self.beginningOfDocument toPosition:textPosition];
}

- (void)setCursorPosition:(NSInteger)position
{
    UITextPosition *textPosition = [self positionFromPosition:self.beginningOfDocument offset:position];
    [self setSelectedTextRange:[self textRangeFromPosition:textPosition toPosition:textPosition]];
}

@end

Upvotes: 1

gabuchan
gabuchan

Reputation: 793

Here's the Swift version of @Chris R. – updated for Swift3

private func selectTextForInput(input: UITextField, range: NSRange) {
    let start: UITextPosition = input.position(from: input.beginningOfDocument, offset: range.location)!
    let end: UITextPosition = input.position(from: start, offset: range.length)!
    input.selectedTextRange = input.textRange(from: start, to: end)
}

Upvotes: 2

Dan J
Dan J

Reputation: 25673

I've finally found a solution for this problem! You can put the text you need inserted into the system pasteboard and then paste it at the current cursor position: 

[myTextField paste:self]

I found the solution on this person's blog:
http://dev.ragfield.com/2009/09/insert-text-at-current-cursor-location.html

The paste functionality is OS V3.0 specific, but I've tested it and it works fine for me with a custom keyboard.

If you go for this solution then you should probably save the user's existing clipboard contents and restore them immediately afterwards.

Upvotes: 3

Alex Cio
Alex Cio

Reputation: 6052

Here is a snippet which works fine for this problem:

- (void)textFieldDidBeginEditing:(UITextField *)textField{
    UITextPosition *positionBeginning = [textField beginningOfDocument];
    UITextRange *textRange =[textField textRangeFromPosition:positionBeginning 
                                                  toPosition:positionBeginning];
    [textField setSelectedTextRange:textRange];
}

Source from @omz

Upvotes: -2

Chris R
Chris R

Reputation: 2895

Controlling cursor position in a UITextField is complicated because so many abstractions are involved with input boxes and calculating positions. However, it's certainly possible. You can use the member function setSelectedTextRange:

[input setSelectedTextRange:[input textRangeFromPosition:start toPosition:end]];

Here's a function which takes a range and selects the texts in that range. If you just want to place the cursor at a certain index, just use a range with length 0:

+ (void)selectTextForInput:(UITextField *)input atRange:(NSRange)range {
    UITextPosition *start = [input positionFromPosition:[input beginningOfDocument] 
                                                 offset:range.location];
    UITextPosition *end = [input positionFromPosition:start
                                               offset:range.length];
    [input setSelectedTextRange:[input textRangeFromPosition:start toPosition:end]];
}

For example, to place the cursor at idx in the UITextField input:

    [Helpers selectTextForInput:input 
                        atRange:NSMakeRange(idx, 0)];

Upvotes: 68

pix0r
pix0r

Reputation: 31280

I don't think there is a way to place the cursor at a particular place in your UITextField (unless you got very tricky and simulated a touch event). Instead, I'd handle formatting when the user has finished editing their text (in textFieldShouldEndEditing:) and if their entry is incorrect, don't allow the text field to finish editing.

Upvotes: 0

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