iOS编程------- Block高级------>Block传值

//
//  AppDelegate.h
//  UI13_Block
//
//  Created by l on 15/9/17.
//  Copyright (c) 2015年 . All rights reserved.
//

#import <UIKit/UIKit.h>

@interface AppDelegate : UIResponder <UIApplicationDelegate>

@property (strong, nonatomic) UIWindow *window;


@end






//
//  AppDelegate.m
//  UI13_Block
//
//  Created by l on 15/9/17.
//  Copyright (c) 2015年 . All rights reserved.
//

#import "AppDelegate.h"
#import "FirstViewController.h"
@interface AppDelegate ()

@end

@implementation AppDelegate
- (void)dealloc{

    [_window release];
    [super dealloc];
}

//定义一个函数
int sum(int x, int y){

    return x + y;
}

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {
    self.window = [[[UIWindow alloc] initWithFrame:[[UIScreen mainScreen] bounds]] autorelease];
    // Override point for customization after application launch.
    self.window.backgroundColor = [UIColor whiteColor];
    [self.window makeKeyAndVisible];


    //函数
    //什么是函数? 就是有特定功能的代码段,函数也是一种数据类型,函数的类型有参数和返回值决定
    //比如:int sum(int x, int y);

    NSLog(@"%d", sum(2, 3));

    //函数指针
    //指针 :是一种类型,存放的是内存的地址
    //指针变量: 指向自身存放地址的内存空间

    //函数也是一种类型,指向函数这种类型的指针,被称为函数指针
    //函数指针 通常指向一类函数,具有相同的参数和返回值的函数
    //比如:int sum(int x, int y);
    //int sub(int x, int y);
    //int mul(int x, int y);

    //定义了一个函数指针变量
    int (*method)(int x, int y) = sum;

    //调用
    NSLog(@"%d", method(3, 5));


    // 二. block
    //block 为匿名函数,存储的是函数体,没有函数名

    //block也是一种类型,为block类型,存储的是函数体
    //block的标志是上划线(托字符) ^

    //1.定义一个block类型的变量
    //int (int x, int y)
    int (^block1)(int x, int y);

    //2.给block赋值
    block1 = ^(int a, int b){

        return a + b;
    };

    block1 = ^(int a, int b){

        return a * b;
    };

    //3.调用

    NSLog(@"%d", block1(10, 10));

    //要求 定义一个block类型变量,block类型为一个NSString参数,返回值为NSInteger类型的block
    //该block具有,将string转化为integer类型

    NSInteger (^block2)(NSString *str);
    block2 = ^(NSString *str){

        return [str integerValue];
    };

    NSLog(@"%ld", block2(@"123"));


    //block高级使用
    //block主要用来当做参数进行函数回调以及界面间传值

    //1.block作为方法的参数,函数回调
    //2.实现界面间传值

    //firstVC
    FirstViewController *firstVC = [[FirstViewController alloc] init];
    firstVC.title = @"第一个页面";

    UINavigationController *navC = [[UINavigationController alloc] initWithRootViewController:firstVC];

    self.window.rootViewController = navC;

    [navC release];
    [firstVC release];



    return YES;
}


@end






///////////////////////////////////////////////////////////////////




//
//  FirstViewController.h
//  UI13_Block
//
//  Created by l on 15/9/17.
//  Copyright (c) 2015年 . All rights reserved.
//

#import <UIKit/UIKit.h>

@interface FirstViewController : UIViewController

@end






//
//  FirstViewController.m
//  UI13_Block
//
//  Created by l on 15/9/17.
//  Copyright (c) 2015年 . All rights reserved.
//

#import "FirstViewController.h"
#import "SecondViewController.h"


@interface FirstViewController ()

@property (nonatomic, retain) UITextField *textField;

@end

@implementation FirstViewController
- (void)dealloc{

    [_textField release];
    [super dealloc];
}
- (void)viewDidLoad {
    [super viewDidLoad];

    //textfield
    _textField = [[UITextField alloc] initWithFrame:(CGRectMake(50, 100, 200, 50))];
    _textField.borderStyle = UITextBorderStyleRoundedRect;
    _textField.backgroundColor = [UIColor grayColor];
    [self.view addSubview:_textField];

    //nextBaarButton 下一个页面按钮
    UIBarButtonItem *nextBarButton = [[UIBarButtonItem alloc] initWithTitle:@"next" style:(UIBarButtonItemStylePlain) target:self action:@selector(nextAction:)];
    self.navigationItem.rightBarButtonItem = nextBarButton;

    [nextBarButton release];



    // Do any additional setup after loading the view.
}

//nextAction方法
- (void)nextAction:(UIBarButtonItem *)barButton{
    //1.创建
    SecondViewController *secondVC = [[SecondViewController alloc] init];

    //2.设置属性 给第二个页面的block赋值,指定要实现的逻辑

    //block赋值的时候,要注意 重复引用的问题
    //我们不会在block直接使用_属性名,调用,而是通过一个弱引用的xxxself区调用自身的属性

    //为了解决block的强引用造成的无法释放问题

    //MRC
    __block typeof (self) blockSelf = self;//typeof(self)作用是,返回一个弱引用的self,不会造成引用计数增加问题,因此,不会重复引用.

    //ARC
    __weak typeof (self) weakSelf = self;


    secondVC.secondBlock = ^(NSString *text){

        self.textField.text = text;

    };

    //3.push
    [self.navigationController pushViewController:secondVC animated:YES];
    [secondVC release];
}


- (void)didReceiveMemoryWarning {
    [super didReceiveMemoryWarning];
    // Dispose of any resources that can be recreated.
}

/*
#pragma mark - Navigation

// In a storyboard-based application, you will often want to do a little preparation before navigation
- (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender {
    // Get the new view controller using [segue destinationViewController].
    // Pass the selected object to the new view controller.
}
*/

@end






////////////////////////////////////////////////////////////////////





//
//  SecondViewController.h
//  UI13_Block
//
//  Created by l on 15/9/17.
//  Copyright (c) 2015年 . All rights reserved.
//

#import <UIKit/UIKit.h>
//起别名,MyBlock 指代void(^MyBlock) (NSString *string)类型
typedef void(^MyBlock) (NSString *string);

@interface SecondViewController : UIViewController

@property (nonatomic, retain) UITextField *textField;

//给第二个页面设置一个myblock类型的实例变量
@property (nonatomic, copy) MyBlock secondBlock;
//*** block类型为实例变量,必须用copy修饰
//把block变量,从栈区拷贝到堆区.

@end







//
//  SecondViewController.m
//  UI13_Block
//
//  Created by l on 15/9/17.
//  Copyright (c) 2015年 . All rights reserved.
//

#import "SecondViewController.h"



@interface SecondViewController ()


@end

@implementation SecondViewController
- (void)dealloc{

    [_textField release];

    //block release
    Block_release(_secondBlock);

    [super dealloc];
}

- (void)viewDidLoad {
    [super viewDidLoad];

    //textfield
    _textField = [[UITextField alloc] initWithFrame:(CGRectMake(50, 100, 200, 50))];
    _textField.borderStyle = UITextBorderStyleRoundedRect;
    _textField.backgroundColor = [UIColor grayColor];
    [self.view addSubview:_textField];

    //backBarButton 返回上一级页面按钮
    UIBarButtonItem *backBarButton = [[UIBarButtonItem alloc] initWithTitle:@"back" style:(UIBarButtonItemStylePlain) target:self action:@selector(backAction:)];
    self.navigationItem.rightBarButtonItem = backBarButton;

    [backBarButton release];



    // Do any additional setup after loading the view.
}

//backAction方法
- (void)backAction:(UIBarButtonItem *)barButtonItem{

    _secondBlock(_textField.text);

    [self.navigationController popViewControllerAnimated:YES];
}


- (void)didReceiveMemoryWarning {
    [super didReceiveMemoryWarning];
    // Dispose of any resources that can be recreated.
}

/*
#pragma mark - Navigation

// In a storyboard-based application, you will often want to do a little preparation before navigation
- (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender {
    // Get the new view controller using [segue destinationViewController].
    // Pass the selected object to the new view controller.
}
*/

@end