block传值

block传值

其实block传值个人感觉跟代理很相似.也是从后往前传.//流程:1.后一个界面定义一个block,并且定义一个属性block2.在后一个界面返回前一个界面的瞬间,(即:创建完成一个界面之后),调用block;3.前一个界面实现block的实现4.后一个界面在合适的机会, 让(传的值以参数的形式 含在block的参数里)

代码如下:

[objc] view plaincopy<pre name="code" class="objc">#import "FirstViewController.h"#import "SecondViewController.h"#import "UIButton+Create.h"@interface FirstViewController (){UILabel * _label;}@end@implementation FirstViewController- (void)dealloc{[_label release];[super dealloc];}- (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil{self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil];if (self) {// Custom initialization}return self;}- (void)viewDidLoad{[super viewDidLoad];self.view.backgroundColor = [UIColor redColor];self.navigationItem.title = @"首页";self.view.userInteractionEnabled = YES;/*** 1.创建一个UIButton,* 2.并添加响应事件,从首页跳转到第二个页面.*/UIButton * button = [UIButton systemButtonWithFrame:CGRectMake(100, 120, 50, 50) title:@"Push" target:self action:@selector(didClickButtonAction)];button.userInteractionEnabled = YES;[self.view addSubview:button];/*** 1.在第1个界面创建一个UILabel* 2.把第二页输入框输入的字符串,通过block内部实现传过来* 3.然后通过赋值给UILabel*/_label = [[UILabel alloc]initWithFrame:CGRectMake(50, 80, 200, 30)];_label.backgroundColor = [UIColor greenColor];[self.view addSubview:_label];// Do any additional setup after loading the view.}- (void)didClickButtonAction{/*** 1.用push的方法推出下一个页面* 2.把第二页输入框输入的字符串,通过block内部实现传过来* 3.从而实现把输入框输入的字符串,传到UILabel上.*/SecondViewController * secondVC = [[SecondViewController alloc]init];secondVC.blocks=^(NSString * str){_label.text = str;};[self.navigationController pushViewController:secondVC animated:YES];[secondVC release];}- (void)didReceiveMemoryWarning{[super didReceiveMemoryWarning];// Dispose of any resources that can be recreated.}@end

[objc] view plaincopy<pre name="code" class="objc">#import <UIKit/UIKit.h>typedef void(^block)(NSString * str) ;@interface SecondViewController : UIViewController@property (nonatomic,copy)block blocks;@end

[objc] view plaincopy#import "SecondViewController.h"#import "UIButton+Create.h"#import "FirstViewController.h"@interface SecondViewController (){UITextField * _textField;//创建一个输入框}@end@implementation SecondViewController- (void)dealloc{[_textField release];[super dealloc];}- (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil{self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil];if (self) {// Custom initialization}return self;}- (void)viewDidLoad{[super viewDidLoad];self.view.backgroundColor = [UIColor orangeColor];self.navigationItem.title = @"第二页";/*** 1.创建一个UIButton,* 2.并添加响应事件,从第二个页面返回到首页.*/UIButton * button = [UIButton systemButtonWithFrame:CGRectMake(100, 120, 50, 50) title:@"Back" target:self action:@selector(didClickButtonAction)];[self.view addSubview:button];/*** 1.在第二个界面创建一个输入框**/_textField = [[UITextField alloc]initWithFrame:CGRectMake(50, 80, 200, 30)];_textField.borderStyle = UITextBorderStyleRoundedRect;[self.view addSubview:_textField];// Do any additional setup after loading the view.}- (void)didClickButtonAction{[objc] view plaincopy//调用block方法,把<span style="font-family: Arial;">_textField.text作为参数传过去</span>_blocks(_textField.text);[self.navigationController popToRootViewControllerAnimated:YES];}- (void)didReceiveMemoryWarning{[super didReceiveMemoryWarning];// Dispose of any resources that can be recreated.}@end