iOS--NSNotification

ViewController.m##

#import "ViewController.h"

@interface ViewController ()<UITextFieldDelegate>


@property (weak, nonatomic) IBOutlet UITextField *myTextField;


@end

@implementation ViewController

- (void)viewDidLoad {
    [super viewDidLoad];
    
    //注册消息
    [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(changeTheme:) name:@"change" object:nil];
    
    _myTextField.delegate = self;
    //键盘弹出调节界面高度
    [[NSNotificationCenter defaultCenter]addObserver:self selector:@selector(adjustHeight:) name:UIKeyboardWillShowNotification object:nil];
    //键盘回收返回原界面高度
    [[NSNotificationCenter defaultCenter]addObserver:self selector:@selector(backHeight:) name:UIKeyboardWillHideNotification object:nil];
    
}

-(void)adjustHeight:(NSNotification *)sender{
    
    [UIView beginAnimations:@"键盘弹出" context:nil];
    
    [UIView setAnimationDuration:0.5];
    
    [UIView setAnimationTransition:UIViewAnimationTransitionFlipFromRight forView:self.view cache:YES];
    
    
    CGRect newRect = self.view.frame;
    
    newRect.origin.y -= 250;
    
    self.view.frame  = newRect;
    
    [UIView commitAnimations];
    
}

-(void)backHeight:(NSNotification *)sender{
    
    [UIView beginAnimations:@"键盘落下" context:nil];
    
    [UIView setAnimationDuration:0.3];
    
     [UIView setAnimationTransition:UIViewAnimationTransitionFlipFromLeft forView:self.view cache:YES];
    
    CGRect newRect = self.view.frame;
    
    newRect.origin.y += 250;
    
    self.view.frame  = newRect;
    
    [UIView commitAnimations];

}



//接收消息后做出的反应
-(void)changeTheme:(NSNotification *)sender{
    
    self.view.backgroundColor = sender.userInfo[@"color"] ;
    
}


-(BOOL)textFieldShouldReturn:(UITextField *)textField{
    
    [textField resignFirstResponder];
    return YES;
}

- (void)didReceiveMemoryWarning {
    [super didReceiveMemoryWarning];
    // Dispose of any resources that can be recreated.
}

@end

SecondViewController.m##

#import "SecondViewController.h"

@interface SecondViewController ()

@end

@implementation SecondViewController

- (void)viewDidLoad {
    [super viewDidLoad];
    
    //注册消息
    [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(changeTheme:) name:@"change" object:nil];
    
    
}

-(void)changeTheme:(NSNotification *)sender{
    
     self.view.backgroundColor = sender.userInfo[@"color"] ;
    
    
}


- (void)didReceiveMemoryWarning {
    [super didReceiveMemoryWarning];
    // Dispose of any resources that can be recreated.
}

/*
#pragma mark - Navigation

// In a storyboard-based application, you will often want to do a little preparation before navigation
- (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender {
    // Get the new view controller using [segue destinationViewController].
    // Pass the selected object to the new view controller.
}
*/

@end

ThirdViewController.m##

#import "ThirdViewController.h"

@interface ThirdViewController ()

@end

@implementation ThirdViewController

- (void)viewDidLoad {
    [super viewDidLoad];

    //注册消息
    [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(changeTheme:) name:@"change" object:nil];
    
}

////发送消息(向所有name是@"change"的页面发送消息)
//[[NSNotificationCenter defaultCenter]postNotificationName:@"change" object:nil userInfo:@{@"color":[UIColor lightGrayColor]}];//userInfo:发送消息时传递的信息(字典);


-(void)changeTheme:(NSNotification *)sender{
    
    NSNotification *notification = sender;
     self.view.backgroundColor = notification.userInfo[@"color"] ;
    
}


- (void)didReceiveMemoryWarning {
    [super didReceiveMemoryWarning];
    // Dispose of any resources that can be recreated.
}

/*
#pragma mark - Navigation

// In a storyboard-based application, you will often want to do a little preparation before navigation
- (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender {
    // Get the new view controller using [segue destinationViewController].
    // Pass the selected object to the new view controller.
}
*/

@end

SettingViewController.m##

#import "SettingViewController.h"

@interface SettingViewController ()

@end

@implementation SettingViewController

- (void)viewDidLoad {
    [super viewDidLoad];
    // Do any additional setup after loading the view.
}


- (IBAction)changeCloor:(UIButton *)sender {
    
    NSLog(@"修改所有页面背景颜色");
    
    //发送消息(向所有name是@"change"的页面发送消息)
    [[NSNotificationCenter defaultCenter]postNotificationName:@"change" object:nil userInfo:@{@"color":[UIColor lightGrayColor]}];//userInfo:发送消息时传递的信息(字典);
    //object 这个参数有点像二次确认的意思，就是在同一个通知name的情况下还可以通过object再次进行细分通知。就拿上面这个小demo说，如果object为空，接收方会接受所有名字为giveName的通知。但是如果object不为空，接收方就会只接收名字为giveName的而且object正确的通知。
}


// [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(changeTheme:) name:@"change" object:nil];


/*
   通知  原理一问度娘一大堆解释，我在这就用我自己的理解给大家狂谈一下，刚刚上面也提及到了，基本通知有三步走：post发送通知，NSNotificationCenter通知中心处理通知，addobserve接收通知。不论发送通知还是接收通知都只有一条路可走，那就是通知中心。如果你还能找到另外一个路走，那你真是酷炫牛逼呲啦冒火花了。通知中心是一个单例类，管理系统的所有通知事件，不论是我们手动发出的还是系统的通知。在创建通知的时候有两种情况：
 
 1、只是传递动作，不传递具体的信息内容详情
 
 - (void)postNotificationName:(NSString *)aName object:(nullable id)anObject;
 
 2、传递具体的信息内容，用字典传递。
 
 - (void)postNotificationName:(NSString *)aName object:(nullable id)anObject userInfo:(nullable NSDictionary *)aUserInfo;
 
 
 */

- (void)didReceiveMemoryWarning {
    [super didReceiveMemoryWarning];
    // Dispose of any resources that can be recreated.
}

@end