objective-c - NSMutableArray 到 NSString 并将 NSString 传递到另一个 View IOS5.1

Question

我有一个 NSMutableArray 名称。我希望将 NSMutableArray 内的数据(选定的名称)作为文本传递到另一个 View 的标签。

FriendsController.m:

- (void)viewDidLoad {
    [super viewDidLoad];
    arrayOfNames=[[NSMutableArray alloc] init];
    arrayOfIDs=[[NSMutableArray alloc] init];
    userName=[[NSString alloc] init];
}

- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath {
    long long fbid = [[arrayOfIDs objectAtIndex:indexPath.row]longLongValue];
    NSString *user=[NSString stringWithFormat:@"%llu/picture",fbid];
    [facebook requestWithGraphPath:user andDelegate:self];

    userName=[NSString stringWithFormat:@"%@",[arrayOfNames objectAtIndex:indexPath.row]];
    FriendDetail *profileDetailName = [[FriendDetail alloc] initWithNibName: @"FriendDetail" bundle: nil];

    profileDetailName.nameString=userName;

    [profileDetailName release];
}

- (void)request:(FBRequest *)request didLoad:(id)result  {
    if ([result isKindOfClass:[NSData class]]) {
        transferImage = [[UIImage alloc] initWithData: result];
        FriendDetail *profileDetailPicture = [[FriendDetail alloc] initWithNibName: @"FriendDetail" bundle: nil];

        [profileDetailPicture view];
        profileDetailPicture.profileImage.image= transferImage;

        profileDetailPicture.modalTransitionStyle = UIModalTransitionStyleCrossDissolve;
        [self presentModalViewController:profileDetailPicture animated:YES];

        [profileDetailPicture release];
    }   
} 

在 FriendDetail.h 中

NSString nameString;
IBOutlet UILabel *profileName;
@property (nonatomic, retain) UILabel *profileName;
@property (nonatomic, retain) NSString *nameString;

在 FriendDetail.m

- (void)viewDidLoad
{
    [super viewDidLoad];
    profileName.text=nameString;
}

nameString在第二个 Controller (FriendDetail)中返回 nil 。当我在firstcontroller中设置断点时，我看到nameString内部的字符串是正确的，但之后它返回 nil不知怎的。

------------------------编辑------------------------ -----------------

根据答案，我稍微改进了我的代码 FriendsController.h

 FriendDetail *friendController;
@property (strong, nonatomic) FriendDetail *friendController;

FriendsController.m

- (void)viewDidLoad
{
    [super viewDidLoad];
    arrayOfNames=[[NSMutableArray alloc] init];
    arrayOfIDs=[[NSMutableArray alloc] init];
    arrayOfThumbnails=[[NSMutableArray alloc] init];
    userName=[[NSString alloc] init];

    friendController= [[FriendDetail alloc] initWithNibName: @"FriendDetail" bundle: nil];
}

-(void)request:(FBRequest *)request didLoad:(id)result{
    if ([result isKindOfClass:[NSData class]])
    {
        transferImage = [[UIImage alloc] initWithData: result];
        friendController.nameString=userName;

        [friendController view];
        friendController.profileImage.image= transferImage;


       friendController.modalTransitionStyle = UIModalTransitionStyleCrossDissolve;
        [self presentModalViewController:friendController animated:YES];
    }
   //this is how i take facebook friends list
         if ([result isKindOfClass:[NSDictionary class]]){
             items = [[(NSDictionary *)result objectForKey:@"data"]retain];
             for (int i=0; i<[items count]; i++) {
            NSDictionary *friend = [items objectAtIndex:i];
            long long fbid = [[friend objectForKey:@"id"]longLongValue];
            NSString *name = [friend objectForKey:@"name"];
            NSLog(@"id: %lld - Name: %@", fbid, name);
            [arrayOfNames addObject:[NSString stringWithFormat:@"%@", name]];
            [arrayOfIDs addObject:[NSNumber numberWithLongLong:fbid]];

        }
    }
}

- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath
{

    long long fbid = [[arrayOfIDs objectAtIndex:indexPath.row]longLongValue];
    NSString *user=[NSString stringWithFormat:@"%llu/picture",fbid];

    userName=[NSString stringWithFormat:@"%@",[arrayOfNames objectAtIndex:indexPath.row]];

    [facebook requestWithGraphPath:user andDelegate:self]; 
    [username retain]
}

现在，当我第一次选择行时，它会发送名称。当我回到桌面 View 并选择另一个名称时，它会显示旧名称。

如果我删除[username retain]在didSelectRowAtIndexPath:它仍然发送 nil至nameString

当我在 didSelectRowAtIndexPath: 设置断点时在行`

userName=[NSString stringWithFormat:@"%@",[arrayOfNames objectAtIndex:indexPath.row]]`

我可以看到userName = @"Adam Dart"哪个是正确的

在我的第二个断点 friendController.nameString=userName; 行我看到nameString =nil和userName = Variable is not CFString

ARC 设置为“否”

Answer 1

该值为 nil，因为您没有在 request:didLoad: 函数中传递该值。

在函数didSelectRowAtIndexPath中，您创建了另一个ViewController的本地实例并设置了nameString的值，但您没有立即呈现 View 并释放ViewController。实际上，您在这几行代码中什么也没做:

FriendDetail *profileDetailName = [[FriendDetail alloc] initWithNibName: @"FriendDetail" bundle: nil];
profileDetailName.nameString = userName;
[profileDetailName release];

在函数 request:didLoad: 中，您再次使用图像创建另一个 ViewController 的本地实例。但这个实例只是该函数的本地实例，这意味着与 didSelectRowAtIndexPath 中创建的实例没有关系。

你需要做的是，在didSelectRowAtIndexPath中先记住点击的行的名称，这里你不必创建ViewController实例。当请求完成时，将图像和名称设置给 Controller ，然后呈现它。但是您应该避免用户同时单击不同的行，因为您不知道请求何时完成。