Question

这是我的代码，它在我发送Label值时有效，但当我传递为字符串时显示为null请帮助我... 建议我将一个String传递给第二个视图

这是我的第一个vc“AssignmentsDetailsJson.j”

#import <UIKit/UIKit.h>
#import "DocumentsViewController.h"

@interface AssignmentsDetailsJson : <UITabBarControllerDelegate,UITabBarDelegate>

@end

这是AssignmentsDetailsJson.m文件

#import "AssignmentsDetailsJson.h"

@interface AssignmentsDetailsJson ()
@property(strong, nonatomic) DocumentsViewController *controllerB;

@end

@implementation AssignmentsDetailsJson

- (void)tabBarController:(UITabBarController *)tabBarController didSelectViewController:(UIViewController *)viewController
{
    self.controllerB = (DocumentsViewController *)                                    [tabBarController.viewControllers objectAtIndex:1];

    self.controllerB.data= @"yooooooooooo!";

}

- (void)viewDidLoad 
{
   [super viewDidLoad];

   self.tabBarController.delegate = self;

}

这是第二个视图DocumentsViewController.h

#import <UIKit/UIKit.h>
#import "AssignmentsDetailsJson.h"

@interface DocumentsViewController : UIViewController
@property (weak, nonatomic) IBOutlet UILabel *aLabelInControllerB;
@property (nonatomic, strong) NSString *data;

@property(strong, nonatomic) DocumentsViewController *controllerB;
@end

这是DocumentsViewController.m

#import "DocumentsViewController.h"

@interface DocumentsViewController ()


@end

@implementation DocumentsViewController
@synthesize data;
- (void)viewDidLoad 
{
    [super viewDidLoad];

     NSLog(@"hooo %@",data);
}

- (void)didReceiveMemoryWarning
{
  [super didReceiveMemoryWarning];
  // Dispose of any resources that can be recreated.
}

Answer 1

您可以使用delegate或NSNotification执行此操作，风险高于delegate。

Answer 2

问题是在传递数据之前会调用viewDidLoad。这就是你在NSLog语句中没有得到任何输出的原因。而不是tabBarControllerDidSelect [...]尝试以下内容：

- (BOOL)tabBarController:(UITabBarController *)tabBarController shouldSelectViewController:(UIViewController *)viewController {
  if ([viewController isKindOfClass:[SecondViewController class]]) {
    ((SecondViewController *)viewController).data = @"passed some data";
  }
  return YES;
}

UITabBarController将字符串值传递给第二个TabView

2 个答案: