UI控件笔记（七）：UI之五种传值方式 代理\单例\缓存\通知\正向

一、传值简介

AAAA
代理： 1V1 A->B，B回A的时候使用

BBBB
单例： 无所谓
整个应用都要用的数据，存一个应用内的全局值，ios6？ios7

CCCC 缓存：
为所谓 整个应用都要用的数据，保证下次启动还有点数据，账号、密码

DDDD 通知： 1V多
犯懒的时候，A发通知，B观察通知，B在A之前，比较占资源

E 正向传值：A->B，B的内容由A来定，那么B应该有一个属性，A->B的时候给B的属性赋值

二、举例

1、AppDelegate.m文件中的写法

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {

// Override point for customization after application launch.

self.window = [[UIWindow
alloc] initWithFrame:[UIScreen
mainScreen].bounds];

self.window.backgroundColor = [UIColor
whiteColor];

FirstViewController *first = [[FirstViewController
alloc]
init];

UINavigationController *nav = [[UINavigationController
alloc]
initWithRootViewController:first];

[first release];

self.window.rootViewController = nav;

[nav release];

[self.window
makeKeyAndVisible];

return
YES;

}

2、FirstViewController.m文件中的写法

#import "FirstViewController.h"

#import "SecondViewController.h"

#import "SingleTon.h"

@interface
FirstViewController ()<SecondDelegate>//AAAA
代理声明可以写这里

@end

@implementation FirstViewController

- (void)viewDidLoad {

[super
viewDidLoad];

self.view.backgroundColor = [UIColor
redColor];

//DDDD
通知中心

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

//第三个参数：这里专门等着接的通知名

//第一个和第二个参数：截到对应通知名的通知后，用第一个参数去执行第二个参数的方法

// Do any additional setup after loading the view.

}

-(void)notify:(NSNotification*)noti

{

UIColor *color = [noti
object];//发通知的时候传过的参数，就是这里的这个noti，无论什么类型的参数，都用object去解析，解析完了，发的时候是什么类型，就是什么类型

self.view.backgroundColor = color;

}

//touch事件，去第二个页面

-(void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event

{

NSLog(@"松手了");

SecondViewController *second = [[SecondViewController
alloc]
init];

second.delegate =
self;//AAAA
被触发者的第二件事儿

[self.navigationController
pushViewController:second animated:YES];

[second release];

}

//AAAA 实现代理的方法

-(void)getColor:(UIColor *)color

{

self.view.backgroundColor = color;

}

-(void)viewWillAppear:(BOOL)animated

{

static int num =
0;

if(num != 0)

{

[self single];

[self userdefaults];

}

num++;

}

-(void)single//BBBB
单例

{

SingleTon *single = [SingleTon
shareInstance];//还是那个

self.view.backgroundColor = single.color;

}

-(void)userdefaults//CCCC
缓存

{

NSArray *colorArr =
@[[UIColor
redColor],[UIColor
yellowColor],[UIColor
blueColor]];//数组存三色

int num = [[[NSUserDefaults
standardUserDefaults] objectForKey:@"color"]
intValue];

self.view.backgroundColor = colorArr[num];

}

3、SecondViewController.h文件中的写法

#import <UIKit/UIKit.h>

AAAA 声明代理

@protocol SecondDelegate <NSObject>

-(void)getColor:(UIColor*)color;

@end

@interface SecondViewController :
UIViewController

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

@end

4、SecondViewController.m文件中的写法

#import "SecondViewController.h"

#import "SingleTon.h"

@interface
SecondViewController ()

@end

@implementation SecondViewController

- (void)viewDidLoad {

[super
viewDidLoad];

self.view.backgroundColor = [UIColor
greenColor];

[self makeBtn];

// Do any additional setup after loading the view.

}

-(void)makeBtn

{

NSArray *arr =
@[@"red",@"yellow",@"blue"];

for(int i =0;i<arr.count;i++)

{

UIButton *btn = [UIButton
buttonWithType:UIButtonTypeRoundedRect];

btn.frame =
CGRectMake(0,
64+i*60, 320,
60);

[btn setTitle:arr[i]
forState:UIControlStateNormal];

[btn addTarget:self
action:@selector(btnDown:)
forControlEvents:UIControlEventTouchUpInside];

[self.view
addSubview:btn];

btn.tag =
1000+i;

}

}

-(void)btnDown:(UIButton*)btn

{

NSArray *colorArr =
@[[UIColor
redColor],[UIColor
yellowColor],[UIColor
blueColor]];//数组存三色

//该传值了

[self delegateMethod:colorArr[btn.tag -
1000]]; AAAA

[self singleMethod:colorArr[btn.tag -
1000]]; BBBB

[self userdefaultsMethod:btn.tag -
1000]; CCCC

[self notificationMethod:colorArr[btn.tag -
1000]]; DDDD

[self.navigationController
popViewControllerAnimated:YES];

}

-(void)delegateMethod:(UIColor*)color//AAAA
代理

{

[self.delegate
getColor:color];

}

-(void)singleMethod:(UIColor*)color//BBBB
单例

{

SingleTon *single = [SingleTon
shareInstance];

single.color = color;//给单例的属性赋值

}

-(void)userdefaultsMethod:(int)color//CCCC
缓存

{

NSUserDefaults *user = [NSUserDefaults
standardUserDefaults];

[user setObject:[NSString
stringWithFormat:@"%d",color]
forKey:@"color"];

[user synchronize];

}

-(void)notificationMethod:(UIColor*)color//DDDD
通知

{

//1、做一个通知中心

NSNotificationCenter *center = [NSNotificationCenter
defaultCenter];

//2、做一个通知内容

NSNotification *notify = [NSNotification
notificationWithName:@"pp"
object:color];//第一个参数：通知名，第二个参数：通知携带的参数

//3、用通知中心把通知内容post出去，然后就不管了

[center postNotification:notify];//中心调方法，内容是参数

}

5、SingleTon.h单例写法 BBBB

#import <Foundation/Foundation.h>

#import <UIKit/UIKit.h>

@interface SingleTon :
NSObject

@property(nonatomic,retain)UIColor *color;//用来保存全局颜色的

+(id)shareInstance;

@end

6、SingleTon.m单例写法 BBBB

#import "SingleTon.h"

static SingleTon *single =
nil;

@implementation SingleTon

+(id)shareInstance

{

static dispatch_once_t onceToken;

dispatch_once(&onceToken, ^{

single = [SingleTon
alloc];//这里只走一次

});

return single;

}

@end