UIViewController界面跳转时的值传递

由FirstViewController跳转到SecondViewController的过程中，伴随着值的正向传递，在SecondViewController的操作完成之后，返回到FirstViewController的过程中也伴随着值的反向传递。

FirstViewController------>------SecondViewController的正向值传递：

FirstViewController.swift

import UIKit

class FirstViewController: UIViewController {

override func viewDidLoad()
{
super.viewDidLoad()

self.view.backgroundColor = UIColor.whiteColor()
self.title = "FirstView"
self.navigationController?.navigationBar.barTintColor = UIColor.whiteColor()

var btn = UIButton(frame: CGRectMake(30, 100, 100, 40))
btn.backgroundColor = UIColor.greenColor()
btn.setTitle("点击跳转", forState: UIControlState.Normal)
btn.addTarget(self, action: "toSecondView", forControlEvents: UIControlEvents.TouchDown)
self.view.addSubview(btn)
}

func toSecondView() -> Void
{
let secondViewContrller = SecondViewController()
secondViewContrller.titleText = "From FirstViewController"
secondViewContrller.titleColor = UIColor.redColor()
self.navigationController?.pushViewController(secondViewContrller, animated: true)
}

override func didReceiveMemoryWarning()
{
super.didReceiveMemoryWarning()
}

}

SecondViewController.swift

import UIKit

class SecondViewController: UIViewController
{

var titleText: String?
var titleColor: UIColor?

override func viewDidLoad()
{
super.viewDidLoad()

self.view.backgroundColor = UIColor.whiteColor()

self.title = titleText
self.navigationController?.navigationBar.barTintColor =titleColor
}

override func didReceiveMemoryWarning()
{
super.didReceiveMemoryWarning()
}

}

FirstViewController------>------SecondViewController的反向值传递：

［说明］UIViewController跳转时值的反向传递有两种方式，代理和闭包。


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( - ) 代理的方法

SecondViewController.swift

import UIKit

// 自定义的代理
protocol SecondViewDelegate: NSObjectProtocol
{
// 在代理中定义方法, 修改title的内容
func changeTitleContent(title: String)
// 修改背景颜色
func changeBackgroundColor(color: UIColor)
}

class SecondViewController: UIViewController
{

var delegate: SecondViewDelegate?

override func viewDidLoad()
{
super.viewDidLoad()
self.view.backgroundColor = UIColor.whiteColor()
self.title = "SecondView"

var btn = UIButton(frame: CGRectMake(20, 90, 170, 40))
btn.backgroundColor = UIColor.redColor()
btn.setTitle("返回", forState: UIControlState.Normal)
btn.addTarget(self, action: "backToFirst", forControlEvents: UIControlEvents.TouchDown)
self.view.addSubview(btn)
}

func backToFirst() -> Void
{
delegate?.changeTitleContent("Back From SecondViewController")
delegate?.changeBackgroundColor(UIColor.purpleColor())
self.navigationController?.popViewControllerAnimated(true)
}

override func didReceiveMemoryWarning()
{
super.didReceiveMemoryWarning()
}

}

FirstViewController.swift

import UIKit

// 在FirstViewController中实现SecondViewDelegate
class FirstViewController: UIViewController, SecondViewDelegate
{

override func viewDidLoad()
{
super.viewDidLoad()

self.view.backgroundColor = UIColor.whiteColor()
self.title = "FirstView"

var btn = UIButton(frame: CGRectMake(30, 100, 100, 40))
btn.backgroundColor = UIColor.greenColor()
btn.setTitle("点击跳转", forState: UIControlState.Normal)
btn.addTarget(self, action: "toSecondView", forControlEvents: UIControlEvents.TouchDown)
self.view.addSubview(btn)
}

func toSecondView() -> Void
{
let secondViewContrller = SecondViewController()
secondViewContrller.delegate = self
self.navigationController?.pushViewController(secondViewContrller, animated: true)
}

override func didReceiveMemoryWarning()
{
super.didReceiveMemoryWarning()
}

func changeBackgroundColor(color: UIColor)
{ //重写SecondViewDelegate的方法
self.view.backgroundColor = color
}

func changeTitleContent(title: String)
{ //重写SecondViewDelegate的方法
self.title = title
}

}

( - ) 闭包的方式回传数据

SecondViewController.swift

import UIKit

class SecondViewController: UIViewController
{

// 定义一个闭包
var changeContent: ((title: String, color: UIColor) -> Void)?

override func viewDidLoad()
{
super.viewDidLoad()
self.view.backgroundColor = UIColor.whiteColor()
self.title = "Second"

var btn = UIButton(frame: CGRectMake(20, 90, 170, 40))
btn.backgroundColor = UIColor.redColor()
btn.setTitle("返回", forState: UIControlState.Normal)
btn.addTarget(self, action: "backToFirst", forControlEvents: UIControlEvents.TouchDown)
self.view.addSubview(btn)
}

func backToFirst() -> Void
{
// 通过闭包回传数据
changeContent?(title: "From SecondViewController", color: UIColor.purpleColor())
self.navigationController?.popViewControllerAnimated(true)
}

override func didReceiveMemoryWarning()
{
super.didReceiveMemoryWarning()
}

}

FirstViewController.swift

import UIKit

class FirstViewController: UIViewController
{

override func viewDidLoad()
{
super.viewDidLoad()
self.view.backgroundColor = UIColor.whiteColor()
self.title = "First"

var btn = UIButton(frame: CGRectMake(30, 100, 100, 40))
btn.backgroundColor = UIColor.greenColor()
btn.setTitle("点击跳转", forState: UIControlState.Normal)
btn.addTarget(self, action: "toSecondView", forControlEvents: UIControlEvents.TouchDown)
self.view.addSubview(btn)
}

func toSecondView() -> Void
{
let secondViewController = SecondViewController()
// 设置值的接收方式
secondViewController.changeContent =
{
(title: String, color: UIColor) in
self.title = title
self.view.backgroundColor = color
}
self.navigationController?.pushViewController(secondViewController, animated: true)
}

override func didReceiveMemoryWarning() {
super.didReceiveMemoryWarning()
}

}