             }
         }
     }
-    public func scrollViewContentOffsetDidChange(change:AnyObject?)->Void{
+    private func scrollViewContentOffsetDidChange(change:AnyObject?)->Void{
         if self.scrollView != nil {
             if (self.scrollView!.dragging) {
                 

        
    }
    private func configLayoutConstraint(){
        titleLabel.translatesAutoresizingMaskIntoConstraints = false
        var constraints = [NSLayoutConstraint]()
        var left = NSLayoutConstraint(item: titleLabel, attribute: .Leading, relatedBy: .Equal, toItem: self, attribute: .Leading, multiplier: 1, constant: 0)
        var right = NSLayoutConstraint(item: titleLabel, attribute: .Trailing, relatedBy: .Equal, toItem: self, attribute: .Trailing, multiplier: 1, constant: 0)
        var top = NSLayoutConstraint(item: titleLabel, attribute: .Top, relatedBy: .Equal, toItem: self, attribute: .Top, multiplier: 1, constant: 0)

        case Loading
    }
    
    /*!
        这个方法来设置不同状态的文案
     */
    public func setTitle(title:String, forState:ScrollViewRefreshState){
        switch forState {
        case .PullDownToRefresh:
