swift场景转换2和委托

下面是3个视图控制器，用连线来进行跳转！还有一个是用id来进行跳转。如图选中线设置identifiter属性 ，把<去场景>按钮的identifiter 改成c

写一个A场景的视图控制器

import UIKit

class ViewController: UIViewController {

    override func viewDidLoad() {
        super.viewDidLoad()
        // Do any additional setup after loading the view, typically from a nib.
    }

    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
        // Dispose of any resources that can be recreated.
    }
    //这是id 按钮的关联函数
    @IBAction func jumpToB(sender: UIButton) {
       //还可以传值
        performSegueWithIdentifier("B", sender: "kangkang")
    }
    override func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject?) {
        if(segue.identifier=="B"){
        
        print(sender)
        }
        else if(segue.identifier=="c"){
            
          print("to  场景")
            
        }
        
        }
    }

用委托实现更新数据如下图！点击button去b，然后点传值返回

写一个a场景的视图控制器

import UIkit
class Aviewcontroll:UIViewController{
    //var str:String="lable"
    @IBOutlet weak var mylabel: UILabel!
    override func viewDidLoad() {
        super.viewDidLoad()
        print("数据初始化lab:",mylabel.text)
     //   mylabel.text= str
        // Do any additional setup after loading the view.
    }
    
    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
        
    }
    
  
    @IBAction func tojumpB(sender: UIButton) {
        
       let vc = self.storyboard?.instantiateViewControllerWithIdentifier("myAScene") as! BviewControll
        vc.delegate=self
        presentViewController(vc, animated: true, completion: nil)
    }
 
    //说明用上面的方式进行跳转时，不会执行prepareForSegue方法
    override func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject?) {
//                let target = segue.destinationViewController as! BviewControll
//                target.delegate = self
    }
    


}
extension Aviewcontroll : BDelegate{
    func b(controller: BviewControll, data:String){
        print("(data)")
        mylabel.text = data
   
//    str = data
//        print("数据：",str)
    }


}

再写一个b场景的视图控制器

import UIKit

class BviewControll:UIViewController{
     var delegate: BDelegate?
    override func viewDidLoad() {
        super.viewDidLoad()
        
        // Do any additional setup after loading the view.
    }
    
    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
        
    }
    override func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject?) {
//      let target = segue.destinationViewController as! Aviewcontroll
//       self.delegate = target
        
    }
    
    @IBAction func jumptoA(sender: UIButton) {
 //返回my self data 数据
        delegate?.b(self, data:"my self data")
       dismissViewControllerAnimated(true, completion: nil)
        
    }




}

再写一个delegate

import Foundation

protocol BDelegate{

    //    func someMethod()
    //这是为了满足ios开发中委托的标准写法，
    //并不是强制要求这样写，简单来说就是为了装逼
    
    //装逼标准：1.名字：delegate前面的内容，
    //2.第一个参数是对应的类型
    //3.真正需要传递的数据
    func b(controll:BviewControll,data:String)

}

这样就可以传值返回了label里就有值了！