iOS-UITextView size.height大于其中的文本

我创建了以下代码：

var sampleText = "Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum. Nam liber te conscient to factor tum poen legum odioque civiuda. Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum. Nam liber te conscient to factor tum poen legum odioque civiuda."

    var emptyView = UIView()
    self.view.addSubview(emptyView)
    var frame = CGRect()
    frame = emptyView.frame
    frame.origin.x = 0
    frame.origin.y = 10
    frame.size.width = self.view.frame.width
    emptyView.frame = frame
    var textView = UITextView()
    textView.text = sampleText
    var frameTextView = CGRect()
    frameTextView = emptyView.frame
    textView.frame = frameTextView
    textView.font = UIFont(name: "Helvetica Neue", size: 12)
    textView.textColor = UIColor.blackColor()
    emptyView.addSubview(textView)
    textView.sizeToFit()
    textView.layoutIfNeeded()

当printtextView.frame.size.height时，我得到了159,5，这比这个视图在屏幕上显示的要大得多。为什么我的textView.frame这么高