prepareForSegue帶我到一個空白頁面

Question

我必須查看控制器（UpcomingReleaseViewController和ReleaseController）。

我正在使用JSON來填充我的應用程序。

從我的應用程序的主頁是UpcomingReleasesViewController，一旦你點擊一個單元格它應該帶你到發佈頁面，並顯示更多的信息，但由於某種原因，每次你點擊一個單元格，它會帶你到一個空白頁。

ReleaseView.h

@interface ReleaseViewController : UIViewController 
@property (weak, nonatomic) IBOutlet UITextView *releaseView; 
@property (strong, nonatomic) NSString *release_name; 
@end 

ReleaseView.m

@interface ReleaseViewController() 

@end 

@implementation ReleaseViewController 

@synthesize releaseView = _releaseView; 

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

- (void)viewDidLoad 
{ 
    [super viewDidLoad]; 

    self.releaseView.text = self.release_name; 
} 

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

@end 

UpcomingReleaseViewController.m

#import "UpcomingReleasesViewController.h" 
#import "UpcomingRelease.h" 
#import "ReleaseViewController.h" 

@interface UpcomingReleasesViewController() 

@end 

@implementation UpcomingReleasesViewController 

- (void)viewDidLoad 
{ 
    [super viewDidLoad]; 

    NSURL *upcomingReleasesURL = [NSURL URLWithString:@"http://obscure-lake-7450.herokuapp.com/upcoming.json"]; 

    NSData *jsonData = [NSData dataWithContentsOfURL:upcomingReleasesURL]; 

    NSError *error = nil; 

    NSDictionary *dataDictionary = [NSJSONSerialization JSONObjectWithData:jsonData options:0 error:&error]; 

    self.upcomingReleases = [NSMutableArray array]; 

    NSArray *upcomingReleasesArray = [dataDictionary objectForKey:@"upcoming_releases"]; 

    for (NSDictionary *upcomingReleaseDictionary in upcomingReleasesArray) { 
     UpcomingRelease *upcomingRelease = [UpcomingRelease upcomingReleaseWithReleaseName:[upcomingReleaseDictionary objectForKey:@"release_name"]]; 
     upcomingRelease.release_price = [upcomingReleaseDictionary objectForKey:@"release_price"]; 
     upcomingRelease.release_date = [upcomingReleaseDictionary objectForKey:@"release_date"]; 
     upcomingRelease.thumbnail = [upcomingReleaseDictionary objectForKey:@"thumbnail"]; 
     upcomingRelease.url = [NSURL URLWithString:[upcomingReleaseDictionary objectForKey:@"url"]]; 
     [self.upcomingReleases addObject:upcomingRelease]; 
    } 
} 


- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath 
{ 
    static NSString *CellIdentifier = @"Cell"; 
    UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier forIndexPath:indexPath]; 

    UpcomingRelease *upcomingRelease = [self.upcomingReleases objectAtIndex:indexPath.row]; 

    NSData *imageData = [NSData dataWithContentsOfURL:upcomingRelease.thumbnailURL]; 
    UIImage *image = [UIImage imageWithData:imageData]; 

    cell.imageView.image = image; 
    cell.textLabel.text = upcomingRelease.release_name; 
    cell.detailTextLabel.text = [NSString stringWithFormat:@"%@ — $%@",[upcomingRelease formattedDate], upcomingRelease.release_price]; 

    return cell; 
} 

#pragma mark - View Upcoming Release 

- (void) prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender { 
    if ([segue.identifier isEqualToString:@"showRelease"]) { 
     ReleaseViewController *rvc = (ReleaseViewController *)[segue destinationViewController]; 
     rvc.release_name = [self.upcomingReleasesArray objectAtIndex:[[self.tableView indexPathForSelectedRow] row]]; 
    } 
} 


@end 

故事板Segue命名正確（showRelease），並將UITextView鏈接到我的ReleaseViewController（releaseView）。可能與即將發佈的Release數組有關係嗎？我是iOS新手，我不知道問題可能是什麼。

Answer 1

雖然要通過單擊表格單元格進行導航，但應該使用tableView的didSelectRowAtIndexPath委託方法。在這個方法中，只是使用你在prepareForSegue中使用的東西，並刪除這個prepareForSegue。因爲prepareForSegue會在下一個View之前被調用。 didSelect會在點擊單元格時被調用。當你想在調用下一個視圖之前設置任何數據時，你應該使用prepareForSegue。