Move Cursor to Location Objective-C

Question

I have a UITextView and I want have two buttons. When the user taps the back button I want the cursor to move back 1 character. When they tap to forward button the cursor should move forward 1 character. How could I do this?

Answer 1

I wrote it out for you, referencing the answer linked below. You can drop the code I wrote into a basic project and try it out.

The solution idea:

You can programmatically select a block of text by specifying the range of text to select (see reference). What's a range, you ask? It's basically a starting position and a length. Since you only care about the cursor position, you can ignore the length (i.e. keep it at zero) and adjust the starting position of the "selection" by +1 or -1.

Reference:

Can I select a specific block of text in a UITextField?

Code Explanation:

In the code below, there are two buttons (Forward and Back) and a target method for each of them that changes the cursor position in the UITextView. Note that tv is the class variable/property for your UITextView (and needs to be declared as such).

The Code:

- (void)viewDidLoad {
    [super viewDidLoad];
    UIButton *forward = [UIButton buttonWithType:UIButtonTypeRoundedRect];
    forward.frame = CGRectMake(20, 20, 100, 50);
    [forward setTitle:@"Forward" forState:UIControlStateNormal];
    [forward addTarget:self action:@selector(moveForward:) forControlEvents:UIControlEventTouchUpInside];

    UIButton *back = [UIButton buttonWithType:UIButtonTypeRoundedRect];
    back.frame = CGRectMake(130, 20, 100, 50);
    [back setTitle:@"Back" forState:UIControlStateNormal];    
    [back addTarget:self action:@selector(moveBack:) forControlEvents:UIControlEventTouchUpInside];

    tv = [[UITextView alloc] initWithFrame:CGRectMake(20, 120, 280, 100)];
    [self.view addSubview:forward];
    [self.view addSubview:back];
    [self.view addSubview:tv];    
}


-(void)moveForward:(id)sender {
    UITextRange *selectedRange = [tv selectedTextRange];
    // Calculate the new position, - for left and + for right

    if (tv.selectedRange.location < tv.text.length) {
        UITextPosition *newPosition = [tv positionFromPosition:selectedRange.start offset:1];

        UITextRange *newRange = [tv textRangeFromPosition:newPosition toPosition:newPosition];

        // Set new range
        [tv setSelectedTextRange:newRange];
    }
}

-(void)moveBack:(id)sender {
    UITextRange *selectedRange = [tv selectedTextRange];
    // Calculate the new position, - for left and + for right

    if (tv.selectedRange.location > 0) {
        UITextPosition *newPosition = [tv positionFromPosition:selectedRange.start offset:-1];

        UITextRange *newRange = [tv textRangeFromPosition:newPosition toPosition:newPosition];

        // Set new range
        [tv setSelectedTextRange:newRange];
    }
}