Question

我无法弄清楚为什么我的segue.identifier总是返回null。我在storboard中设置了segue标识符。

ViewController1

-(void) prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender
{
     NSLog(@"prepared %@",segue.identifier);
     if([[segue identifier] isEqualToString:@"segue1"] ){
     NSLog(@"segue is equal to 1");
     }
 }

ViewController2

- (IBAction)unwindFromSegue:(UIStoryboardSegue *)segue {

    NSLog(@"unwinded %@",segue.identifier);
}

日志消息始终为null，因此如果statement永远不为true。有什么想法我无法获得标识符？

编辑：

我制作了一个全新的测试项目。它是ViewController和SecondViewController的单一视图应用程序。在故事板中，我从View Controller中的按钮到SecondViewController进行了popover segue连接，并将segue标识符设置为segue1。

在SecondViewController上，我创建了一个后退按钮并将其连接到我的ViewController中的unwindFromSegue。我还在SecondViewController中添加了prepareForSegue。

ViewController.h

#import <UIKit/UIKit.h>

@interface ViewController : UIViewController

@end

ViewController.m

#import "ViewController.h"

@interface ViewController ()

@end

@implementation ViewController

- (void)viewDidLoad
{
[super viewDidLoad];
// Do any additional setup after loading the view, typically from a nib.
}

- (void)didReceiveMemoryWarning
{
[super didReceiveMemoryWarning];
// Dispose of any resources that can be recreated.
}
- (IBAction)unwindFromSegue:(UIStoryboardSegue *)segue {
NSLog(@"unwinded %@",segue.identifier);
}
@end

SecondViewController.h

#import <UIKit/UIKit.h>

@interface SecondViewController : UIViewController

@end

SecondViewController.m

#import "SecondViewController.h"

@interface SecondViewController ()

@end

@implementation SecondViewController

- (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)
 nibBundleOrNil
{
self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil];
if (self) {
    // Custom initialization
}
return self;
}

- (void)viewDidLoad
{
[super viewDidLoad];
// Do any additional setup after loading the view.
}

- (void)didReceiveMemoryWarning
{
[super didReceiveMemoryWarning];
// Dispose of any resources that can be recreated.
}
//was just testing unwindFromSegue here. Didn't mean to post here, 
//but I will keep it in with an answer referring to it
//- (IBAction)unwindFromSegue:(UIStoryboardSegue *)segue{
//NSLog(@"unwind in second %@",segue.identifier);
//}


- (void) prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender{
NSLog(@"prepare %@",segue.identifier);

}

@end

希望这会有所帮助。感谢

Answer 1

在故事板中设置segue时，您还必须为其分配标识符。在您的情况下“segue1”。

Answer 2

为什么在SecondViewController中有unwindFromSegue：方法？您没有展开该控制器，它与ViewController中的控制器名称相同。那可能是你的问题。拿出那个，看看是否能解决问题。

segue.identifier isEqualToString：@“segue1”始终为null。 IOS 6.1故事板

2 个答案: