Xcode中使用Picker View和Segue， Size to fit content
调整控件中的内容，会使内容和控件显示出现问题，快速适配 Editor－>Size to fit content 可以快速使控件适配内容，亦或快捷键 command ＋＝，当然，前提选择控件。
使用Picker View 需要实现三个方法，继承UIPickerViewDataSource,UIPickerViewDelegate
func numberOfComponentsInPickerView(pickerView: UIPickerView) -> Int{
return 1;// 列数
}
func pickerView(pickerView: UIPickerView, numberOfRowsInComponent component: Int) -> Int{
return lijians.count; //行数
}
func pickerView(pickerView: UIPickerView, titleForRow row: Int, forComponent component: Int) -> String? {
return lijians[row];
}并且设置代理和数据源
override func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject?) {
if segue.identifier == “A”{ //判断segue，用处极大，判断调转那个页面
let index = Picker.selectedRowInComponent(0)
var vc = segue.destinationViewController as! Second //强制转换成Second，在前一页就可以给后一页赋值，很棒
vc.ss = flag