02-单例-通知-KVO-Block-代理

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#IOS开发 #UI高级 #类 #传值

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本文介绍iOS应用中五种常用的数据传递方法：单例模式、通知、KVO观察者模式、Block闭包及代理模式，并提供了详细的实现代码示例。

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一、单例：

1.定义单例类

@interface single : NSObject

@property (nonatomic, copy) NSString *name;

+ (id)shareInstance;

@end

#import "single.h"

static single *instance = nil;

@implementation single

+ (id)shareInstance
{
    if (instance == nil) {

        instance = [[single alloc] init];

    }
    return instance;
}

@end

2.实现传值

传值者：

single *s = [single shareInstance];

s.name = _lable.text;

接收者：

//视图将要显示时调用

- (void)viewWillAppear:(BOOL)animated
{
single *s1 = [single shareInstance];
lable.text = s1.name;

}

二、通知：

1.发送通知

//取得输入的数据

NSString *text = _textFiekd.text;

NSDictionary *dic = @{
@"key":text

};

//发送通知1

[[NSNotificationCenter defaultCenter] postNotificationName:@"changeValue" object:self userInfo:dic];

[self dismissViewControllerAnimated:YES completion:nil];

//发送通知2

[[NSNotificationCenter defaultCenter] postNotificationName:@"tapAction" object:self];

2.接受通知

//接收通知

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

- (void)changeAction:(NSNotification *)notification {

//取得传递的数据
NSDictionary *dic = notification.userInfo;

_label.text = dic[@"key"];

}

//接受通知

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

- (void)tapAction
{

_isHidden = !_isHidden;

self.navigationController.navigationBar.hidden = _isHidden;

[[UIApplication sharedApplication] setStatusBarHidden:_isHidden];

}

//删除通知

- (void)dealloc
{
[[NSNotificationCenter defaultCenter] removeObserver:self];
}

三、KVO观察者模式

1.观察者

接收值

_secondCtrl = [[SecondViewController alloc] init];

//监听secondCtrl的属性值变化

[_secondCtrl addObserver:self forKeyPath:@"text" options:NSKeyValueObservingOptionNew context:nil];

//接收到消息后触发的方法
- (void)observeValueForKeyPath:(NSString *)keyPath
                      ofObject:(id)object
                        change:(NSDictionary *)change
                       context:(void *)context {

    NSLog(@"change:%@",change);

    NSString *text = [change objectForKey:@"new"];
    _label.text = text;

}

删除观察者

- (void)dealloc
{

[_secondCtrl removeObserver:self forKeyPath:@"happyValue" context:NULL];

}

2.被观察者

定义观察属性

@property(nonatomic, copy)NSString *text;

赋值

self.text = _textFiekd.text;

四、Block

1.要传值的一边定义block

typedef void(^MyBlock)(NSString *text);

@property(nonatomic, copy)MyBlock block;

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

if(_block != nil){

_block(_textFiekd.text);

}

2.接收值的一边

- (void)viewWillAppear:(BOOL)animated {

    [super viewWillAppear:animated];

    secondCtrl.block = ^(NSString *text) {

        _label.text = text;

};

}

五、代理

要传值的一边如下配置：

@protocol sendData <NSObject>

- (void)sendData:(NSString *)text;

@end

@property(nonatomic, assign)id<sendData> delegate;

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

- (IBAction)dismissAction:(id)sender {

if (self.delegate respondsToSelector:@selector(sendData:)) {

[_delegate sendData:_textFiekd.text];
}
[self dismissViewControllerAnimated:YES completion:nil];

}

接收值的一边如下配置：

@interface ViewController ()<sendData>

@property (weak, nonatomic) IBOutlet UILabel *label;

- (IBAction)presentAction:(id)sender {
    SecondViewController *secondCtrl = [[SecondViewController alloc] init];

    secondCtrl.delegate = self;

    [self presentViewController:secondCtrl animated:YES completion:nil];

}

- (void)sendData:(NSString *)text {

    _label.text = text;

}