页面之间传值方式的总结,五种方式,通知,block,代理,单例,NSUERDEFALUT,

@interface DataSource : NSObject
@property (nonatomic, strong) NSString *myName;//单例的属性,用于传值
+(DataSource*)sharedDataSource;//建立单例对象
@end

#import "DataSource.h"

@implementation DataSource
+(DataSource *)sharedDataSource{
    static DataSource *dataSource = nil;
    static dispatch_once_t once;
    dispatch_once(&once, ^{
        dataSource = [DataSource new];
    });
    return dataSource;
}//返回一个静态的本类对象
@end

#import <UIKit/UIKit.h>
#import "SecondViewController.h"
@interface RootViewController : UIViewController<secondViewDelegate>


@end

#import "RootViewController.h"
#import "SecondViewController.h"
#import "DataSource.h"
@interface RootViewController ()
@property (weak, nonatomic) IBOutlet UILabel *nameLabel;

@end

@implementation RootViewController

- (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil
{
    self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil];
    if (self) {
        // Custom initialization
    }
    return self;
}

- (void)viewDidLoad
{
    [super viewDidLoad];
    // 传值方式2:通知:首先注册通知,使用选择器设置接收到通知,调用的方法
    [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(ChangeNameNotification:) name:@"ChangeNameNotification" object:nil];
}
- (IBAction)showSecondView:(id)sender {
    SecondViewController *second = [[SecondViewController alloc] initWithNibName:@"SecondViewController" bundle:nil];
    second.delegate = self;//设置代理,传值方法3:代理
    second.flag = 0;
    [self presentViewController:second animated:YES completion:nil];
}
//4.显示的实现
-(void)showName:(NSString *)nameString{
    self.nameLabel.text = nameString;
}
//传值方式2:通知:接受到通知,调用该方法显示通知
-(void)ChangeNameNotification:(NSNotification*)notification{
    NSDictionary *nameDictionary = [notification userInfo];
    self.nameLabel.text = [nameDictionary objectForKey:@"name"];
}


//传值方法4:block方法,点击对应按钮出发,设置好传值页面的block方法,进行跳转
- (IBAction)showSecondWithBlock:(id)sender {
    SecondViewController *second = [[SecondViewController alloc] initWithNibName:@"SecondViewController" bundle:nil];
    
    second.flag = 1;
    
    [self presentViewController:second animated:YES completion:nil];
    
    
    second.block = ^(NSString *str){
        self.nameLabel.text = str;// 传值方法4:设置block方法为更改接收页面label的文本
    };
}
//传值方法2:通知,不使用时，删掉通知
-(void)dealloc{
    [[NSNotificationCenter defaultCenter] removeObserver:self];
}

-(void)viewDidAppear:(BOOL)animated{
    [super viewDidAppear:animated];
//   通过UserDefault方式取值

    if ([[[NSUserDefaults standardUserDefaults] objectForKey:@"myNameText"] length] != 0) {
        self.nameLabel.text = [[NSUserDefaults standardUserDefaults] objectForKey:@"myNameText"];
        [[NSUserDefaults standardUserDefaults] setObject:@"" forKey:@"myNameText"];
    }//传值方法5:NSUSERDEFAULT,读取沙盒内的plist文件获取值

//传值方法1: 通过单例取值
    DataSource *dataSource = [DataSource sharedDataSource];
    if ([dataSource.myName length] != 0) {
        self.nameLabel.text = dataSource.myName;
        dataSource.myName = @"";
    }//直接设置或者获取单例对象,单例对象只有一个,所以能够用于传值;

}
@end

#import <UIKit/UIKit.h>
//block传值1：定义一个block，参数为字符串
typedef void (^ablock)(NSString *str);
//传值方法3:代理 声明协议及方法
@protocol secondViewDelegate
-(void)showName:(NSString *)nameString;
@end
@interface SecondViewController : UIViewController
@property (nonatomic, weak)id<secondViewDelegate> delegate;//传值方法2:代理.设置代理
@property (nonatomic, copy) ablock block;//传值方法4: 定义一个block属性
@property(nonatomic) NSInteger flag;//当前系统标示（0：其他传值方式；1：block传值方式）
@end

#import "SecondViewController.h"
#import "DataSource.h"
@interface SecondViewController ()
@property (weak, nonatomic) IBOutlet UITextField *nameTextField;
@property (weak, nonatomic) IBOutlet UIButton *delegateMethod;
@property (weak, nonatomic) IBOutlet UIButton *notificationMethod;
@property (weak, nonatomic) IBOutlet UIButton *blockMethod;
@property (weak, nonatomic) IBOutlet UIButton *userDefaultMethod;
@property (weak, nonatomic) IBOutlet UIButton *singletonMethod;

@end

@implementation SecondViewController

- (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil
{
    self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil];
    if (self) {
        // Custom initialization
    }
    return self;
}

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

- (IBAction)Cancel:(id)sender {
    [self dismissViewControllerAnimated:YES completion:nil];
}

//传值方式3:调用代理,直接调用代理,跳转接受页面
- (IBAction)delegateMethod:(id)sender {
    if ([self notEmpty]) {
        [self.delegate showName:self.nameTextField.text];
        [self dismissViewControllerAnimated:YES completion:nil];
    }else{
        [self showAlert];
    }
}

-(IBAction)backDown:(id)sender{
    [self.nameTextField resignFirstResponder];
}
//传值方式2:通知.创建一个通知对象及发送通知
- (IBAction)notificationMethod:(id)sender {
    if ([self notEmpty]) {
        [[NSNotificationCenter defaultCenter] postNotificationName:@"ChangeNameNotification" object:self userInfo:@{@"name":self.nameTextField.text}];
        [self dismissViewControllerAnimated:YES completion:nil];
    }else{
        [self showAlert];
    }
}
//传值方式4:block传值2：在传值页面中，当输入名字，点击对应的确定按钮后,直接调用本身的block方法,由于跳转之前已经设置为更改接受页面的label,传值成功
- (IBAction)blockMethod:(id)sender {
    if ([self notEmpty]) {
        if (self.block) {
            self.block(self.nameTextField.text);
            [self dismissViewControllerAnimated:YES completion:nil];
        }
    }else{
        [self showAlert];
    }
}
//用于检测是否输入框为空
-(BOOL)notEmpty{
    if ([self.nameTextField.text length] == 0) {
        return NO;
    }
    return YES;
}

-(void)showAlert{
    UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"提示" message:@"请输入名字" delegate:self cancelButtonTitle:@"Cancel" otherButtonTitles:@"Ok", nil];
    [alert show];
}

//传值方式5:NSUSERDEFAULT 通过文件或者UserDefault方式存值
- (IBAction)userDefaultMethod:(id)sender {
    if ([self notEmpty]) {
        [[NSUserDefaults standardUserDefaults] setObject:self.nameTextField.text forKey:@"myNameText"];//使用kvc方法设置
        [self dismissViewControllerAnimated:YES completion:nil];
    }else{
        [self showAlert];
    }
}

//传值方式1:单例 写入要传入的数据(单例对象只有一个,所以能够进行传值)
- (IBAction)singletonMethod:(id)sender {
    if ([self notEmpty]) {
        DataSource *dataSource = [DataSource sharedDataSource];
        dataSource.myName = self.nameTextField.text;
        [self dismissViewControllerAnimated:YES completion:nil];
    }else{
        [self showAlert];
    }
}

-(void)viewWillAppear:(BOOL)animated{
    [super viewWillAppear:animated];
    if (self.flag == 0) {
        self.delegateMethod.hidden = NO;
        self.notificationMethod.hidden = NO;
        self.blockMethod.hidden = YES;
        self.userDefaultMethod.hidden = NO;
        self.singletonMethod.hidden = NO;
    }else{
        self.delegateMethod.hidden = YES;
        self.notificationMethod.hidden = YES;
        self.blockMethod.hidden = NO;
        self.userDefaultMethod.hidden = YES;
        self.singletonMethod.hidden = YES;
    }
}//根据flag来决定哪些按钮不显示
@end