iOS-常见的页面传值方式

背景：

iOS开发中，页面传值是必不可少的。很多时候，控制器之间的传值是很常见。下面，我总结几种常见的页面传值方式，记录下来，方便以后查看。

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预备工作：

准备两个控制器，第一个控制有一个UIButton和一个UILabel，第二个控制器有一个UITextField和一个UIButton。
以下的页面传值都围绕这两个控制器来演示。
代码如下：

#import "OneViewController.h"#import "TwoViewController.h"@interface OneViewController ()/**显示文字的Label*/@property(nonatomic,strong) UILabel *ZFLabel;/**跳到第二个控制器的Button*/@property(nonatomic,strong) UIButton *ZFBtn;@end@implementation OneViewController- (void)viewDidLoad {    [super viewDidLoad];    self.view.backgroundColor = [UIColor whiteColor];    [self setupControls];}-(void)ZFBtnAction{    TwoViewController *twoVC = [[TwoViewController alloc] init];    twoVC.str = @"我是属性传值";    [self presentViewController:twoVC animated:YES completion:^{    }];}-(void)setupControls{    self.ZFLabel = [[UILabel alloc] initWithFrame:CGRectMake(100, 100, 200, 40)];    self.ZFLabel.backgroundColor = [UIColor cyanColor];    [self.view addSubview:self.ZFLabel];    self.ZFBtn = [UIButton buttonWithType:UIButtonTypeSystem];    self.ZFBtn.frame = CGRectMake(100, CGRectGetMaxY(self.ZFLabel.frame) + 10, 150, 30);    [self.ZFBtn setTitle:@"跳转到第二个控制器" forState:UIControlStateNormal];    [self.ZFBtn addTarget:self action:@selector(ZFBtnAction) forControlEvents:UIControlEventTouchUpInside];    [self.view addSubview:self.ZFBtn];}@end

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#import "TwoViewController.h"@interface TwoViewController ()/**输入框*/@property(nonatomic,strong) UITextField *ZFTextField;/**回到第一个控制器的Button*/@property(nonatomic,strong) UIButton *ZFBtn;@end@implementation TwoViewController- (void)viewDidLoad {    [super viewDidLoad];    self.view.backgroundColor = [UIColor whiteColor];    [self setupControls];}-(void)ZFBtnAction{    [self dismissViewControllerAnimated:YES completion:^{    }];}-(void)setupControls{    self.ZFTextField = [[UITextField alloc] initWithFrame:CGRectMake(100, 100, 200, 40)];    self.ZFTextField.borderStyle = UITextBorderStyleRoundedRect;    [self.view addSubview:self.ZFTextField];    self.ZFBtn = [UIButton buttonWithType:UIButtonTypeSystem];    self.ZFBtn.frame = CGRectMake(100, CGRectGetMaxY(self.ZFTextField.frame) + 10, 150, 30);    [self.ZFBtn setTitle:@"回到第一个控制器" forState:UIControlStateNormal];    [self.ZFBtn addTarget:self action:@selector(ZFBtnAction) forControlEvents:UIControlEventTouchUpInside];    [self.view addSubview:self.ZFBtn];}@end

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一、属性传值

属性传值，顾名思义，在控制器里面定义一个属性，然后把值赋值给该控制器属性。属性传值，常用于正向传值，即一个控制器跳转到另一个控制器时候，把值传递给第二个控制器。

核心代码：

OneViewController控制器：

-(void)ZFBtnAction{    TwoViewController *twoVC = [[TwoViewController alloc] init];    twoVC.str = @"我是属性传值";    [self presentViewController:twoVC animated:YES completion:^{    }];}

TwoViewController控制器：

self.ZFTextField.text = self.str;

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二、单例传值

单例传值，就是创建一个单例对象，然后把值付给单例对象的属性。无论在哪个控制器，只要调用这个单例对象，就能获取单例对象属性的值。单例传值，可以用于正向、反向传值。

单例对象：

#import <Foundation/Foundation.h>@interface singleton : NSObject@property(nonatomic,strong) NSString *str;/** 获取单例对象 @return 当前对象 */+(singleton *)shareInstance;@end

#import "singleton.h"@implementation singleton+(singleton *)shareInstance{    static singleton *zfInstance;    if (!zfInstance) {        zfInstance = [[singleton alloc] init];    }    return zfInstance;}@end

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OneViewController控制器:

-(void)ZFBtnAction{    TwoViewController *twoVC = [[TwoViewController alloc] init];    singleton *zfInstance =  [singleton shareInstance];    zfInstance.str = @"我是单例传值";    [self presentViewController:twoVC animated:YES completion:^{    }];}

TwoViewController控制器：

    singleton *zfInstance = [singleton shareInstance];    self.ZFTextField.text = zfInstance.str;

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三、NSUserDefaults传值

每个应用程序都有一个自己的沙盒，而NSUserDefaults就是存在于沙盒里面，系统已经为我们创建好了，我们只需要直接使用就好。NSUserDefaults可以用于正向、反向传值。

OneViewController控制器：

-(void)ZFBtnAction{    TwoViewController *twoVC = [[TwoViewController alloc] init];    NSUserDefaults *ud = [NSUserDefaults standardUserDefaults];    [ud setObject:@"我是NSUserDefaults传值" forKey:@"ZFKey"];    [ud synchronize];    [self presentViewController:twoVC animated:YES completion:^{    }];}

TwoViewController控制器：

    NSUserDefaults *ud = [NSUserDefaults standardUserDefaults];    NSString *str = [ud objectForKey:@"ZFKey"];    self.ZFTextField.text = str;

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四、代理传值

代理传值，是苹果开发中最经典的传值方式，常用语反向传值，即从一个控制器到另一个控制器，再由第二个控制器返回到第一个控制器，并且把值从第二个控制器传回到第一个控制器。代理传值比较麻烦，需要定义委托方、代理，而代理需要遵守协议。

OneViewController控制器：

@interface OneViewController ()<transmitValueDelegate>/**显示文字的Label*/@property(nonatomic,strong) UILabel *ZFLabel;/**跳到第二个控制器的Button*/@property(nonatomic,strong) UIButton *ZFBtn;@end@implementation OneViewController- (void)viewDidLoad {    [super viewDidLoad];    self.view.backgroundColor = [UIColor whiteColor];    [self setupControls];}-(void)ZFBtnAction{    TwoViewController *twoVC = [[TwoViewController alloc] init];    twoVC.delegate = self;    [self presentViewController:twoVC animated:YES completion:^{    }];}-(void)transmitStr:(TwoViewController *)twoVC str:(NSString *)str{    self.ZFLabel.text = str;}

TwoViewController控制器：

#import <UIKit/UIKit.h>@class TwoViewController;@protocol transmitValueDelegate<NSObject>@optional-(void)transmitStr:(TwoViewController *)twoVC str:(NSString *)str;@end@interface TwoViewController : UIViewController@property(nonatomic,weak) id <transmitValueDelegate> delegate;@end

-(void)ZFBtnAction{    if ([self.delegate respondsToSelector:@selector(transmitStr:str:)]) {        [self.delegate transmitStr:self str:@"我是代理传值"];    }    [self dismissViewControllerAnimated:YES completion:^{    }];}

五、Block传值

Block传值是苹果推荐的一种传值方式，和代理传值一样，常用语反向传值。Block传值写法比代理传值简单，也是比较流行的一种写法。

OneViewController控制器：

-(void)ZFBtnAction{    TwoViewController *twoVC = [[TwoViewController alloc] init];    twoVC.ZFBlock = ^(NSString *str) {        self.ZFLabel.text = str;    };    [self presentViewController:twoVC animated:YES completion:^{    }];}

TwoViewController控制器：

#import <UIKit/UIKit.h>@interface TwoViewController : UIViewController@property(nonatomic,copy) void(^ZFBlock)(NSString *);@end

-(void)ZFBtnAction{    self.ZFBlock(@"我是block传值");    [self dismissViewControllerAnimated:YES completion:^{    }];}

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六、通知传值

在苹果开发中，通知更是常见。我们用不但可以用通知进行传值，还能用通知给其他控制器发送其他信号、消息，比如键盘弹出消息等等。通知传值不但可以一对一，还可以一对多，多对多。
OneViewController控制器:

- (void)viewDidLoad {    [super viewDidLoad];    self.view.backgroundColor = [UIColor whiteColor];    [self setupControls];    [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(receiveMessage:) name:@"notiTransmitValue" object:nil];}-(void)receiveMessage:(NSNotification *)noti{    self.ZFLabel.text = noti.userInfo[@"key"];}

TwoViewController控制器：

-(void)ZFBtnAction{    [[NSNotificationCenter defaultCenter] postNotificationName:@"notiTransmitValue" object:nil userInfo:@{@"key":@"我是通知传值"}];    [self dismissViewControllerAnimated:YES completion:^{    }];}