IOS三种传值方式

将“A“ VC中的值传到”B“VC中

一、协议

1、创建一个协议（protocol）

2、在A中声明协议

@property (nonatomic,assign)id <SendBackMsg> bDelegate;

3、在A中调用协议：

- (IBAction)goBackBtn:(UIButton *)sender {

if (self.bDelegate && [self.bDelegate respondsToSelector:@selector(sendMsgWithName:andPwd:)]) {

[self.bDelegate sendMsgWithName:self.redNameTF.text andPwd:self.redPwdTF.text];

}

[self dismissViewControllerAnimated:YES completion:nil];

}

4、在B中实现协议、初始化协议

//实现协议方法

-(void)sendMsgWithName:(NSString *)aName andPwd:(NSString *)aPwd

{

self.welcomeLb.text = [NSString stringWithFormat:@"欢迎,%@,%@",aName,aPwd];

}

//初始化

self.redVC.aDelegate = self;

二、代码块（block）

1、进行代码块定义，定义在A.h中，

typedef void(^SendMsg)(NSString *,NSString *);//声明

@property (nonatomic,strong) SendMsg aBlock;

2、进行代码块调用在A.m中

self.aBlock(self.blueNameTF.text,self.bluePwdTF.text);

3、在B.m中进行代码块实现

//防治block引用self（防止循环引用）

// __weak HomeViewController *weakSelf = self;

__unsafe_unretained HomeViewController *weakSelf = self;

self.blueVC.aBlock = ^(NSString *aName,NSString *aPwd){

NSLog(@"代码块的实现");weakSelf.welcomeLb.text = [NSString stringWithFormat:@"代码块方式：%@，%@",aName,aPwd];

};

三、通知

1、在A.m中创建通知：

NSDictionary *dic = [NSDictionary dictionaryWithObjectsAndKeys:self.greenNameTF.text,@"name",self.greenPwdTF.text,@"pwd", nil];

//创建通知

NSNotification *notifacation = [NSNotification notificationWithName:@"MSG" object:self userInfo:dic];

//获取通知

[[NSNotificationCenter defaultCenter]postNotification:notifacation];

2、在b.m中注册通知

- (void)viewDidLoad {

[super viewDidLoad];

// Do any additional setup after loading the view.

self.welcomeLb.text = [NSString stringWithFormat:@"欢迎你,%@,%@",[self.infoDict objectForKey:@"name"],[self.infoDict objectForKey:@"password"]];

//注册通知

[[NSNotificationCenter defaultCenter]addObserver:self selector:@selector(doSomething:) name:@"MSG" object:nil];

}

//———---

-(void)doSomething:(NSNotification *)notificat

{

NSDictionary *infoDict = notificat.userInfo;

NSString *aName = [infoDict objectForKey:@"name"];

NSString *aPwd = [infoDict objectForKey:@"pwd"];

self.nameTf.text = aName;

self.pwdTf.text = aPwd;

}

3、销毁通知

-(void)dealloc

{

[[NSNotificationCenter defaultCenter]removeObserver:self name:@"BlueSendMsg" object:nil];

}