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翻译自stackoverflow的问题
前向传递数据：
例如你有ViewControllerA和ViewControllerB，从ViewcontrollerA向ViewcontrollerB传递一个BOOL变量：
（1）在ViewControllerB.h创建一个属性
@property (nonatomic, assign) BOOL *isSomethingEnabled;
（2）在ViewcontrollerA中引入头文件
#import "ViewControllerB.h"
当点击didSelectRowAtIndex或者IBAction的时候可以用以下代码设置ViewControllerB的属性
ViewControllerB *viewControllerB = [[ViewControllerB alloc] initWithNib:@"ViewControllerB" bundle:nil]; viewControllerB.isSomethingEnabled = YES; [self pushViewController:viewControllerB animated:YES];
用Segue前向传递数据：
用以下方法传递数据：
-(void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender
（1）在ViewControllerB.h创建一个属性
@property (nonatomic, assign) BOOL *isSomethingEnabled;
（2）在ViewcontrollerA中引入头文件
#import "ViewControllerB.h"
（3）建立一个从ViewControllerA到ViewControllerB的segue，不妨取名为showDetailSegue
（4）实现方法：
-(void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender{
if([segue.identifier isEqualToString:@"showDetailSegue"]){
ViewControllerB *controller = (ViewControllerB *)segue.destinationViewController;
controller.isSomethingEnabled = YES;
}
}
如果你的view是嵌套在navigation controller里
-(void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender{
if([segue.identifier isEqualToString:@"showDetailSegue"]){
UINavigationController *navController = (UINavigationController *)segue.destinationViewController;
ViewControllerB *controller = (ViewControllerB *)navController.topViewController;
controller.isSomethingEnabled = YES;
}
}
后向传递数据：
ViewControllerA里面点击某些按钮，跳转到ViewControllerB，里面的事件执行完成后，又要跳转回ViewControllerA，并且把一些数据传递回ViewControllerA。这里需要用到代理模式。
（1）在ViewControllerB.h中，#import下，@interface上声明一个协议
@protocol ViewControllerBDelegate <NSObject> - (void)addItemViewController:(ViewControllerB *)controller didFinishEnteringItem:(NSString *)item; @end
（2）在ViewControllerB.h设置一个delegate属性
@property (nonatomic, weak) id <ViewControllerBDelegate> delegate;
（3）在ViewControllerB中，当我们退出这个ViewController的时候
NSString *itemToPassBack = @"Pass this value back to ViewControllerA"; [self.delegate addItemViewController:self didFinishEnteringItem:itemToPassBack];
（4）在ViewControllerA.h中，引入头文件并实现协议
#import "ViewControllerB.h" @interface ViewControllerA : UIViewController <ViewControllerBDelegate>
（5）在ViewControllerA.m中，
- (void)addItemViewController:(ViewControllerB *)controller didFinishEnteringItem:(NSString *)item
{
NSLog(@"This was returned from ViewControllerB %@",item);
}
（6）设置代理
ViewControllerB *viewControllerB = [[ViewControllerB alloc] initWithNib:@"ViewControllerB" bundle:nil]; viewControllerB.delegate = self [[self navigationController] pushViewController:viewControllerB animated:YES];
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原文地址：http://www.cnblogs.com/leizh007/p/4441187.html
