How to insert text at cursor position of another application on Mac OSX Application (like OSK)?

Question

I'm trying to create an OSX application which would be a replica of On Screen keyboard. Is it possible to insert some text into the cursor position of another active application? Thanks in advance!

Answer 1

It is possible. Accessibility enables to change content of other applications, but your app can't be sandboxed and thus not available via AppStore.

CFTypeRef focusedUI;
AXUIElementCopyAttributeValue(AXUIElementCreateSystemWide(), kAXFocusedUIElementAttribute, &focusedUI);

if (focusedUI) {
    CFTypeRef textValue, textRange;
    // get text content and range
    AXUIElementCopyAttributeValue(focusedUI, kAXValueAttribute, &textValue);
    AXUIElementCopyAttributeValue(focusedUI, kAXSelectedTextRangeAttribute, &textRange);

    NSRange range;
    AXValueGetValue(textRange, kAXValueCFRangeType, &range);
    // replace current range with new text
    NSString *newTextValue = [(__bridge NSString *)textValue stringByReplacingCharactersInRange:range withString:newText];
    AXUIElementSetAttributeValue(focusedUI, kAXValueAttribute, (__bridge CFStringRef)newTextValue);
    // set cursor to correct position
    range.length = 0;
    range.location += text.length;
    AXValueRef valueRef = AXValueCreate(kAXValueCFRangeType, (const void *)&range);
    AXUIElementSetAttributeValue(focusedUI, kAXSelectedTextRangeAttribute, valueRef);

    CFRelease(textValue);
    CFRelease(textRange);
    CFRelease(focusedUI);
}

This code does not check for errors and makes assumption that focused element is text area.