#import <UIKit/UIKit.h>//聲明一個協議@PRotocol SendValue<NSObject>//定義一個方法- (void)sendBtnTitle:(NSString *)title;@end@interface FirstViewController : UIViewController// 定義代理@property (nonatomic, assign) id <SendValue>delegate;// 創建一個正向傳值的屬性@property (nonatomic,copy) NSString *currentTitle;@end

- (void)didButton{    NSArray *btntitles = [NSArray arrayWithObjects:@"按鍵一",@"按鍵二",@"按鍵三", nil];        for (int i=0; i<btntitles.count; i++) {        UIButton *btn = [UIButton buttonWithType:UIButtonTypeSystem];        //改變按鍵字體顏色        [btn setTitleColor:[UIColor blackColor] forState:UIControlStateNormal];        [btn setTitle:[btntitles objectAtIndex:i] forState:UIControlStateNormal];
        // 如果按鈕的標題和屬性中的 _currentTitle 相同，即和根頁面中的導航條的 title 一樣         if([_currentTitle isEqualToString:btn.currentTitle]){
            //開啟選中狀態            btn.selected = YES;            btn.tintColor = [UIColor whiteColor];        }        [btn setTitleColor:[UIColor redColor] forState:UIControlStateSelected];        [btn addTarget:self action:@selector(titlebtnClicked:) forControlEvents:UIControlEventTouchUpInside];        btn.frame = CGRectMake(80, 140+60*i, self.view.frame.size.width-160, 40);        btn.backgroundColor = [UIColor whiteColor];        [self.view addSubview:btn];    }}- (void)titlebtnClicked:(UIButton *)btn{            NSString *title = btn.currentTitle;

    // 判斷代理中是否有 sendBtnTitle ：這個函數

    if ([_delegate respondsToSelector:@selector(sendBtnTitle:)]){

        // 代理 執行自己的 sendBtnTitle 函數，傳參是 title

       [_delegate sendBtnTitle:title];

    }

    NSLog(@"%@",title);    [self.navigationController popViewControllerAnimated:YES];    }

#import <UIKit/UIKit.h>#define C(a,b,c,d) [UIColor colorWithRed:a/255.0 green:b/255.0 blue:c/255.0 alpha:d/255.0]#define IMG(name) [UIImage imageNamed:name]#import "FirstViewController.h"//將協議掛過來@interface rootViewController : UIViewController<SendValue>@end

- (void)btnClicked{    FirstViewController *first = [[FirstViewController alloc] init];    //將當前頁面的navigationItem.title傳遞進去    //正向傳值    first.currentTitle = self.navigationItem.title;    //將代理指定為當前rootViewController類的指針    first.delegate = self;    [self.navigationController pushViewController:first animated:YES];}//實現協議定義的方法- (void)sendBtnTitle:(NSString *)title{    self.navigationItem.title = title;}