UI_协议传值

SecondViewController.h#import <UIKit/UIKit.h>1.声明一份协议.@protocol SecondViewControllerDelegate <NSObject>// 创建一个方法.- (void)takeValue:(NSString *)strValue;@end@interface SecondViewController : UIViewController2.声明代理人属性.@property(nonatomic, assign)id<SecondViewControllerDelegate>delegate;@end

SecondViewController.m#import "SecondViewController.h"#import "RootViewController.h"@interface SecondViewController ()@property(nonatomic, retain)UITextField *textField;@end@implementation SecondViewController- (void)dealloc{    [_textField release];    [super dealloc];}- (void)viewDidLoad {    [super viewDidLoad];    // Do any additional setup after loading the view.    self.view.backgroundColor = [UIColor whiteColor];    // 创建textField.    self.textField = [[UITextField alloc] initWithFrame:CGRectMake(100, 100, 150, 50)];    self.textField.layer.borderWidth = 1;    self.textField.layer.cornerRadius = 10;    [self.view addSubview:self.textField];    [_textField release];    // 创建button.    UIButton *button = [UIButton buttonWithType:UIButtonTypeSystem];    button.frame = CGRectMake(100, 200, 150, 50);    [button setTitle:@"返回" forState:UIControlStateNormal];    button.layer.borderWidth = 1;    button.layer.cornerRadius = 10;    [self.view addSubview:button];    [button addTarget:self action:@selector(backAction:) forControlEvents:UIControlEventTouchUpInside];}- (void)backAction:(UIButton *)button {    // 返回上一页.    [self.navigationController popViewControllerAnimated:YES];    3.设置代理人执行的协议方法    [self.delegate takeValue:self.textField.text];    }

RootViewController.m#import "RootViewController.h"#import "SecondViewController.h"4.签订协议@interface RootViewController ()<SecondViewControllerDelegate>@property(nonatomic, retain)UITextField *myTextField;@property(nonatomic, retain)UILabel *myLabel;@end@implementation RootViewController- (void)dealloc{    [_myTextField release];    [_myLabel release];    [super dealloc];}- (void)viewDidLoad {    [super viewDidLoad];    // Do any additional setup after loading the view.    // 创建一个textField.    self.myTextField = [[UITextField alloc] initWithFrame:CGRectMake(100, 100, 150, 50)];    self.myTextField.layer.borderWidth = 1;    self.myTextField.layer.cornerRadius = 10;    [self.view addSubview:self.myTextField];    [_myTextField release];    // 创建label.    self.myLabel = [[UILabel alloc] initWithFrame:CGRectMake(100, 200, 150, 50)];    self.myLabel.layer.borderWidth = 1;    self.myLabel.layer.cornerRadius = 10;    [self.view addSubview:self.myLabel];    [_myLabel release];    // 创建一个下一页的button.    UIButton *button = [UIButton buttonWithType:UIButtonTypeSystem];    button.frame = CGRectMake(100, 300, 150, 50);    [button setTitle:@"下一页" forState:UIControlStateNormal];    button.layer.borderWidth = 1;    button.layer.cornerRadius = 10;    [self.view addSubview:button];    [button addTarget:self action:@selector(buttonAction:) forControlEvents:UIControlEventTouchUpInside];}- (void)buttonAction:(UIButton *)button {        // push下一页.    SecondViewController *secondVC = [[SecondViewController alloc] init];    [self.navigationController pushViewController:secondVC animated:YES];    [secondVC release];5.设置代理人.    secondVC.delegate = self;}6.实现协议方法.- (void)takeValue:(NSString *)strValue {    NSLog(@"%@", strValue);    // 显示在label上    self.myLabel.text = strValue;}