四大传值详解:属性传值,单例传值,代理传值,block传值

一:属性传值

传值情景:从前一个页面向后一个页面传值

a.在后一个页面,根据传值类型和个数,写属性

b.在前一个页面, 为属性赋值

c.在后一个页面, 使用值

例如:

第一个视图:

#import "FirstViewController.h"

// 导入头文件
#import "SecondViewController.h"
@interface FirstViewController ()
@end
@implementation FirstViewController

// 加载一个导航视图
- (void)viewDidLoad {
    [super viewDidLoad];
    self.view.backgroundColor = [UIColor cyanColor];
    // 配置导航栏标题
    self.navigationItem.title = @"FirstVC";
    // 创建导航栏右侧按钮
    [self customRightItem];
    // 创建textField
    [self customTextField];
}
#pragma mark - 创建textField控件方法
- (void)customTextField{
    // 创建控件
    self.textField = [[UITextField alloc]initWithFrame:CGRectMake(100, 100, 120, 40)];
    _textField.borderStyle = UITextBorderStyleRoundedRect;
    [self.view addSubview:_textField];
    [_textField release];
}
#pragma mark - 创建导航栏右侧按钮
- (void)customRightItem{
    UIBarButtonItem *rightItem = [[UIBarButtonItem alloc]initWithTitle:@"跳转" style:UIBarButtonItemStyleDone target:self action:@selector(handleRight:)];
    self.navigationItem.rightBarButtonItem = rightItem;
    [rightItem release];
}
#pragma mark - 导航栏右侧按钮关联方法
- (void)handleRight:(UIBarButtonItem *)sender{
    // 创建跳转到的页面视图
    SecondViewController *secondVC = [[SecondViewController alloc]init];
    // 属性传值第二步
    // 在push之前将_textField的值取出来赋值给secondVC.textString
    // secondVC.textString = _textField.text;

    [self.navigationController pushViewController:secondVC animated:YES];
    [secondVC release];
}
- (void)didReceiveMemoryWarning {
    [super didReceiveMemoryWarning];
}

@end

 *************************************************************

第二个视图:

#import <UIKit/UIKit.h>
@interface SecondViewController : UIViewController
// 属性传值第一步
@property (nonatomic,copy)NSString *textString;

@end

 ===============================

#import "SecondViewController.h"
@interface SecondViewController ()
@end
@implementation SecondViewController
- (void)dealloc
{
    self.textString = nil;
    [super dealloc];
}
- (void)viewDidLoad {
    [super viewDidLoad];
    self.view.backgroundColor = [UIColor lightGrayColor];
    // 配置导航栏标题
    self.navigationItem.title = @"SecondVC";
    // 创建label
    [self customLabel];
    // 属性传值第三步
    // 将属性中存储的值取出来赋值给_label.text
     _label.text = _textString;
}
#pragma mark - 创建label方法
- (void)customLabel{
    // 创建label对象
    self.label = [[UILabel alloc]initWithFrame:CGRectMake(100,100,120,40)];
    _label.layer.cornerRadius = 7;
    _label.backgroundColor = [UIColor cyanColor];// label默认透明,需要赋颜色
    [self.view addSubview:_label];
    [_label release];
}
- (void)didReceiveMemoryWarning {
    [super didReceiveMemoryWarning];
}

@end

 

 

 

二: 单例传值

传值情景:多个页面间的传值(可从前到后,也可从后向前)

a.创建单例类

b.根据参数的个数和类型, 在单例类中写属性

c.内容存入单例

d.从单例中取内容

缺点:

a.创建对象时, 必须使用单例方法, 不能使用alloc+init

b.单例到程序结束才释放, 内部不能存过大的数据

 例子:

注意:(单例传值首先要创建一个单例类)

#import <Foundation/Foundation.h>
// 单例:使用我们自己设计的创建方法,无论在任何地方调用这个方法保证返回的是同一个对象,这个类就叫做单例类
// 注意:单例类不能使用alloc init 创建对象
// 单例的缺点:它所占的堆区的内存永远都不会释放,除非退出程序,所以单例中储存过大的数据
@interface Singleton : NSObject
// 单例传值的第一步:设计单例的创建方法,设计为类方法,方法有返回值,返回值就是在方法内部创建对象
// 单例创建的开头一般都是:share, main, default, stand
+ (Singleton *)shareSingleton;
// 单例传值的第二步:根据要传数据,设置属性
@property (nonatomic,copy)NSString *string;

@end

====================================== 

#import "Singleton.h"
@implementation Singleton
+ (Singleton *)shareSingleton{
    // 创建一个静态区对象指针,保障它的生命周期和程序一样悠长
    // static修饰的变量,初始化方法只走一次
    static Singleton *singleton = nil;
    if (singleton == nil) {
        // 这个对象不能释放
        singleton = [[Singleton alloc]init];
    }
    return singleton;
}

@end

======================================

#import "FirstViewController.h"
#import "Singleton.h"
@interface FirstViewController ()
@end

@implementation FirstViewController
- (void)dealloc
{
    self.textField = nil;
    [super dealloc];
}

- (void)viewDidLoad {
    [super viewDidLoad];
    self.view.backgroundColor = [UIColor cyanColor];
    // 配置导航栏标题
    self.navigationItem.title = @"FirstVC";
    // 创建导航栏右侧按钮
    [self customRightItem];
    // 创建textField
    [self customTextField];
}
#pragma mark - 创建textField控件方法
- (void)customTextField{
    // 创建控件
    self.textField = [[UITextField alloc]initWithFrame:CGRectMake(100, 100, 120, 40)];
    _textField.borderStyle = UITextBorderStyleRoundedRect;
    [self.view addSubview:_textField];
    [_textField release];
}
#pragma mark - 创建导航栏右侧按钮
- (void)customRightItem{
    UIBarButtonItem *rightItem = [[UIBarButtonItem alloc]initWithTitle:@"跳转" style:UIBarButtonItemStyleDone target:self action:@selector(handleRight:)];
    self.navigationItem.rightBarButtonItem = rightItem;
    [rightItem release];
}
#pragma mark - 导航栏右侧按钮关联方法
- (void)handleRight:(UIBarButtonItem *)sender{
    // 创建跳转到的页面视图
    SecondViewController *secondVC = [[SecondViewController alloc]init];

// 单例传值第三步
    [Singleton shareSingleton].string = _textField.text;
  
    [self.navigationController pushViewController:secondVC animated:YES];
    [secondVC release];
}

- (void)didReceiveMemoryWarning {
    [super didReceiveMemoryWarning];
}

 

@end

*************************************

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

@end

 

#import "SecondViewController.h"
#import "Singleton.h"
@interface SecondViewController ()
@property (nonatomic,retain)UILabel *label;
@end

@implementation SecondViewController
- (void)dealloc
{
    self.textString = nil;
    self.label = nil;
    [super dealloc];
}
- (void)viewDidLoad {
    [super viewDidLoad];
    self.view.backgroundColor = [UIColor lightGrayColor];
    // 配置导航栏标题
    self.navigationItem.title = @"SecondVC";
    // 创建导航栏左侧按钮
    [self customLeftItem];
    // 创建导航栏右侧按钮
    [self customRightItem];
    // 创建label
    [self customLabel];
 
    // 单例传值第四部
    _label.text = [Singleton shareSingleton].string;
   
}
#pragma mark - 创建label方法
- (void)customLabel{
    // 创建label对象
    self.label = [[UILabel alloc]initWithFrame:CGRectMake(100,100,120,40)];
    _label.layer.cornerRadius = 7;
    _label.backgroundColor = [UIColor cyanColor];// label默认透明,需要赋颜色
    [self.view addSubview:_label];
    [_label release];
}
#pragma mark - 创建导航栏左侧按钮方法
- (void)customLeftItem{
    UIBarButtonItem *leftItem = [[UIBarButtonItem alloc]initWithTitle:@"返回" style:UIBarButtonItemStyleDone target:self action:@selector(handleLeft:)];
    self.navigationItem.leftBarButtonItem = leftItem;
    [leftItem release];
}
#pragma mark - 导航栏左侧点击关联方法
- (void)handleLeft:(UIBarButtonItem *)sender{
    [self.navigationController popViewControllerAnimated:YES];
}
#pragma mark - 创建导航栏右侧按钮方法
- (void)customRightItem{
    UIBarButtonItem *rightItem = [[UIBarButtonItem alloc]initWithTitle:@"跳转" style:UIBarButtonItemStyleDone target:self action:@selector(handleRightItem:)];
    self.navigationItem.rightBarButtonItem = rightItem;
    [rightItem release];
}
#pragma mark - 导航栏右侧跳转方法
- (void)handleRightItem:(UIBarButtonItem *)sender{
    ThirdViewController *thirdVC = [[ThirdViewController alloc]init];
    [self.navigationController pushViewController:thirdVC animated:YES];
    [thirdVC release];
}

- (void)didReceiveMemoryWarning {
    [super didReceiveMemoryWarning];
}

@end

 

********************************

#import <UIKit/UIKit.h>
@interface ThirdViewController : UIViewController

@end

#import "ThirdViewController.h"
#import "Singleton.h"
@interface ThirdViewController ()
@property (nonatomic,retain)UILabel *label;
@end

@implementation ThirdViewController
- (void)dealloc
{
    self.label = nil;
    [super dealloc];
}

- (void)viewDidLoad {
    [super viewDidLoad];
    self.view.backgroundColor = [UIColor brownColor];
   
    self.navigationItem.title = @"ThinrdVC";
  
    [self customLabel];
 
    // 单例传值
    _label.text = [Singleton shareSingleton].string;
   
}
#pragma mark - 创建label
- (void)customLabel{
    self.label = [[UILabel alloc]initWithFrame:CGRectMake(100, 100, 120, 40)];
    _label.backgroundColor = [UIColor whiteColor];
    [self.view addSubview:_label];
    [_label release];

}

@end

 

 

 

三: 代理传值

传值情景: 从后一个页面向前一个页面传值

a.后一个页面(找代理) 制定协议

b.写delegate属性

c.在合适的时候, 让代理执行协议方法

d.前一个页面(成为代理) 建立关系

e.遵守协议

f.实现协议方法

g.通知代理执行协议方法

 例子:

#import "FirstViewController.h"
#import "SecondViewController.h"
// 代理传值第四步:代理对象所在的类遵循协议
@interface FirstViewController ()<SecondViewControllerDelegate>
@property (nonatomic,retain)UILabel *label;
@end

@implementation FirstViewController
- (void)dealloc
{
    self.label = nil;
    [super dealloc];
}
- (void)viewDidLoad {
    [super viewDidLoad];
    self.view.backgroundColor = [UIColor cyanColor];
   
    self.navigationItem.title = @"FirstVC";
   
    // 创建label
    [self customLabel];
   
    // 创建Button
    [self customButton];
   
}
#pragma mark - 创建label
- (void)customLabel{
    self.label = [[UILabel alloc]initWithFrame:CGRectMake(50,100, 220, 40)];
    _label.backgroundColor = [UIColor lightGrayColor];
    [self.view addSubview:_label];
    [_label release];
}
#pragma mark - 创建Button
- (void)customButton{

UIButton *button = [UIButton buttonWithType:UIButtonTypeSystem];
    button.frame = CGRectMake(130, 180, 50, 50);
    [button setTitle:@"下一级" forState:UIControlStateNormal];
    [self.view addSubview:button];
    [button addTarget:self action:@selector(handleButton:) forControlEvents:UIControlEventTouchUpInside];
}
- (void)handleButton:(UIButton *)sender{
   
    SecondViewController *secondVC = [[SecondViewController alloc]init];
    // 代理传值第三步:指定代理对象
    secondVC.delegate = self;
   
    [self.navigationController pushViewController:secondVC animated:YES];
    [secondVC release];
   
}

// 代理传值第五步:实现协议方法
- (void)passValue:(NSString *)string{
    _label.text = string;

}
- (void)didReceiveMemoryWarning {
    [super didReceiveMemoryWarning];
}

@end

 

************************************

#import <UIKit/UIKit.h>
@protocol SecondViewControllerDelegate <NSObject>
// 代理传值第一步:制订协议
@optional
// 根据要传的数据类型设计方法的参数
- (void)passValue:(NSString *)string;

@end

@interface SecondViewController : UIViewController

// 代理传值第二步:定义代理协议属性
@property (nonatomic,assign)id <SecondViewControllerDelegate>delegate;

@end

 

 

#import "SecondViewController.h"
@interface SecondViewController ()
@property (nonatomic,retain)UITextField *textField;
@end

@implementation SecondViewController
- (void)dealloc
{
    self.textField = nil;
    [super dealloc];
}
- (void)viewDidLoad {
    [super viewDidLoad];
    self.view.backgroundColor = [UIColor orangeColor];
   
    self.navigationItem.title = @"SecondVC";
   
    // 创建texField
    [self customTextField];
   
    // 创建导航左边按钮
    [self customLeft];
   
   
}
#pragma mark - 创建texField
- (void)customTextField{
    self.textField = [[UITextField alloc]initWithFrame:CGRectMake(50, 100, 220, 40)];
    _textField.backgroundColor = [UIColor whiteColor];
    [self.view addSubview:_textField];
    [_textField release];
}
#pragma mark - 创建导航左边按钮
- (void)customLeft{
    UIBarButtonItem *leftItem = [[UIBarButtonItem alloc]initWithTitle:@"返回上一级" style:UIBarButtonItemStyleDone target:self action:@selector(handleLftItem:)];
    self.navigationItem.leftBarButtonItem = leftItem;
    [leftItem release];
}
- (void)handleLftItem:(UIBarButtonItem *)sender{
   
    // 代理传值第六步:在pop之前通知代理对象执行协议中的方法
    // 判断代理对象有没有实现协议中的方法
    if ([_delegate respondsToSelector:@selector(passValue:)]) {
        [_delegate passValue:_textField.text];
    }
    [self.navigationController popViewControllerAnimated:YES];

}

@end

 

 

 

四: block传值

传值情景: 从后一个页面向前一个页面传值(能写成代理传值, 都可以转化成block传值)

后一个页面

a.对block类型重命名

b.写block属性

c.在合适的时候, 调用block

前一个页面

a.为block赋值

例子:

#import "FirstViewController.h"
#import "SecondViewController.h"
@interface FirstViewController ()
@property (nonatomic,retain)UILabel *label;
@end

@implementation FirstViewController
- (void)dealloc
{
    self.label = nil;
    [super dealloc];
}
- (void)viewDidLoad {
    [super viewDidLoad];
    self.view.backgroundColor = [UIColor cyanColor];
   
    self.navigationItem.title = @"FirstVC";
   
    // 创建label
    [self customLabel];
   
    // 创建Button
    [self customButton];
   
}
#pragma mark - 创建label
- (void)customLabel{
    self.label = [[UILabel alloc]initWithFrame:CGRectMake(50,100, 220, 40)];
    _label.backgroundColor = [UIColor lightGrayColor];
    [self.view addSubview:_label];
    [_label release];
}
#pragma mark - 创建Button
- (void)customButton{

UIButton *button = [UIButton buttonWithType:UIButtonTypeSystem];
    button.frame = CGRectMake(130, 180, 50, 50);
    [button setTitle:@"下一级" forState:UIControlStateNormal];
    [self.view addSubview:button];
    [button addTarget:self action:@selector(handleButton:) forControlEvents:UIControlEventTouchUpInside];
}
- (void)handleButton:(UIButton *)sender{

SecondViewController *secondVC = [[SecondViewController alloc]init];
    // block传值第三步:给block属性赋值,存储一段代码块,在合适的时机回调block内所传的值
    secondVC.block = ^(NSString *string){
        _label.text = string;
    };
   
    [self.navigationController pushViewController:secondVC animated:YES];
    [secondVC release];
   

}

 

@end

 

*************************************

#import <UIKit/UIKit.h>
// block传值第一步:给block数据类型起别名
typedef void (^BlockName)(NSString *);
@interface SecondViewController : UIViewController
// block传值第二步:定义block属性
@property (nonatomic,copy)BlockName block;

@end

 

#import "SecondViewController.h"
@interface SecondViewController ()
@property (nonatomic,retain)UITextField *textField;
@end

@implementation SecondViewController
- (void)dealloc
{
    self.textField = nil;
    [super dealloc];
}
- (void)viewDidLoad {
    [super viewDidLoad];
    self.view.backgroundColor = [UIColor orangeColor];
   
    self.navigationItem.title = @"SecondVC";
   
    // 创建texField
    [self customTextField];
    // 创建导航左边按钮
    [self customLeft];
}
#pragma mark - 创建texField
- (void)customTextField{
    self.textField = [[UITextField alloc]initWithFrame:CGRectMake(50, 100, 220, 40)];
    _textField.backgroundColor = [UIColor whiteColor];
    [self.view addSubview:_textField];
    [_textField release];
}
#pragma mark - 创建导航左边按钮
- (void)customLeft{
    UIBarButtonItem *leftItem = [[UIBarButtonItem alloc]initWithTitle:@"返回上一级" style:UIBarButtonItemStyleDone target:self action:@selector(handleLftItem:)];
    self.navigationItem.leftBarButtonItem = leftItem;
    [leftItem release];
}
- (void)handleLftItem:(UIBarButtonItem *)sender{
    // block传值第四步:block属性的调用(类似于代理传值中的通知代理对象实现协议方法过程)
    _block(_textField.text);

[self.navigationController popViewControllerAnimated:YES];
}
- (void)didReceiveMemoryWarning {
    [super didReceiveMemoryWarning];
}

@end