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

Question

I have a UITextField in my iPhone app. I know how to make the text field select all of its text, but how can change the selection? Say I wanted to select the last 5 characte

Answer 1

Just a small addition to the accepted answer. In iOS 5, the following line crashes my app when UITextView's text length is 0 (has no text):

[self textRangeFromPosition:startPosition toPosition:endPosition];

A small workaround is to add a length == 0 check like:

if (textField.text && textField.text.length > 0) {
    // Get current selected range , this example assumes is an insertion point or empty selection
    UITextRange *selectedRange = [textField selectedTextRange];

    // Calculate the new position, - for left and + for right
    UITextPosition *newPosition = [textField positionFromPosition:selectedRange.start offset:-5];

    // Construct a new range using the object that adopts the UITextInput, our textfield
    UITextRange *newRange = [textField textRangeFromPosition:newPosition toPosition:selectedRange.start];

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