title: NSTextField insertText:@"" doesn't work & Xcode doesn't recognize Label
body: <p>i start a cocoaApplication in xcode 4.3.1 for mac and have below problems</p>
  
  <p>1.when i want to connect an outlet to NSLabel, xcode doesn't recognize Label means that when i type NSLabel or UILabel in code doesn't recognize it 
  2.i want to insert text in textfield with [txt insertText:@""] but doesn't work</p>