func collectionView(collectionView: UICollectionView, cellForItemAtIndexPath indexPath: NSIndexPath) -> UICollectionViewCell{
        NSLog("\(indexPath.row)")
        let collectionCell = collectionView.dequeueReusableCellWithReuseIdentifier("collectionCellLocation", forIndexPath: indexPath) as UICollectionViewCell
        
        let cityLocationButton = collectionCell.viewWithTag(1) as! UIButton
        let autoLocationButton = collectionCell.viewWithTag(2) as! UIButton
        if indexPath.row > 0 {
            NSLog("1111111")
            autoLocationButton.hidden = true
            cityLocationButton.setTitle(searchCityList[indexPath.row-1], forState: UIControlState.Normal)
        }else{
            cityLocationButton.hidden = true
        }
        
        //添加手动定位点击事件
        cityLocationButton.tag = indexPath.row
        let tapGestureRecognizer = UITapGestureRecognizer(target: self, action: "clickForCityName:")
        cityLocationButton.addGestureRecognizer(tapGestureRecognizer)
        //添加自动定位点击事件
        autoLocationButton.tag = indexPath.row
        autoLocationButton.addTarget(self, action: "clickAutoLocation:", forControlEvents: UIControlEvents.TouchUpInside)
        
        return collectionCell
    }

刚进来的时候可以正常显示控件，但是reloadData()之后，就报错：

let cityLocationButton = collectionCell.viewWithTag(1) as! UIButton

这一行显示错误信息是：fatal error: unexpectedly found nil while unwrapping an Optional value
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