Viewcontroller之间通信，传递参数

title: ViewController之间通信，传递参数 date: 2016-10-13 11:38 tags: iOS category: 技术笔记 —

从 ` FirstViewController ` 跳转到 ` SecondViewController ` ，当从 ` SecondViewController ` 返回时，如果想把数据回传给 ` FirstViewController ` ，可以用代理的方法， ` FirstViewController ` 中这样使用：

FirstViewController.h
@interface FirstViewController : UIViewController <SecondViewControllerDelegate>

FirstViewController.m
- (void)pushNextViewControl:(UIBarButtonItem *)button{
    SecondViewController * showVC = [[SecondViewController alloc]init];
    showVC.text = _textField.text;
    // 将代理对象设置成SecondViewController
    showVC.delegate = self;
    [self.navigationController pushViewController:showVC animated:YES];
    [showVC release];
}

// FirstViewController实现协议里面的方法
- (void)showViewGiveValue:(NSString *)text{
    _inputLabel.text = text;
}

` SecondViewController ` 需要这样设置代理：

SecondViewController.h
@protocol SecondViewControllerDelegate <NSObject>

@optional
- (void)showViewGiveValue:(NSString *)text;
@end

@interface SecondViewController : UIViewController

@property (nonatomic,copy)NSString * text;
// 定义一个代理
@property (nonatomic,assign)id<SecondViewControllerDelegate> delegate;

@end

SecondViewController.m
- (void)popPerView:(UIBarButtonItem *)barButton{
    // 在页面跳转前将参数传出去
    if ([self.delegate respondsToSelector:@selector(showViewGiveValue:)]) {
        [self.delegate showViewGiveValue:_showTextField.text];
    }
    [self.navigationController popViewControllerAnimated:YES];

}