iOS - Unable to set text of UILabel

Question

Ok let me explain the situation, I have two view controller let's call them first and second.

• FirstViewController inherit from UITableViewController
• SecondViewController inherit From UIViewController

The interface for the SecondViewController is made with Interface Builder and contains a label and an UIProgressView. Both label and UIProgressView outlet are connected with the right files owner (SecondViewController).

a little bit of code, In FirstViewController :

the following method is triggered by a notification

- (void) addTransfer:(NSNotification *)notification{
        
      NSLog(@"notification received");
      NSDictionary *transferInfo = [notification userInfo];
      // I think the problem is here 
      aTransfer = [[DbTransfer alloc] initWithNibName:@"DbTransfer" bundle:nil];
      //
      aTransfer.srcPath = [transferInfo objectForKey:@"srcPath"];
      aTransfer.dstPath = [transferInfo objectForKey:@"dstPath"];
      [aTransfer startTransfer];
      [transfer addObject:aTransfer];
      [self.tableView reloadData];

}

those are the tableView dataSource methods

- (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView {
// Return the number of sections.
   return 1;
}


- (NSInteger)tableView:(UITableView *)tableView 
                                      numberOfRowsInSection:(NSInteger)section   
{
   NSLog(@"%d numberOfRowsInSection",[transfer count]);
   return [transfer count];
}


- (UITableViewCell *)tableView:(UITableView *)tableView 
                               cellForRowAtIndexPath:(NSIndexPath *)indexPath 
{

static NSString *CellIdentifier = @"Cell";
UITableViewCell *cell=[tableView dequeueReusableCellWithIdentifier:CellIdentifier];
if (cell == nil) {
    cell = [[[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault   
                                     reuseIdentifier:CellIdentifier] autorelease];
}

[cell.contentView addSubview:[[transfer objectAtIndex:indexPath.row] view]];
return cell;

}

this is the code of SecondViewController.h

@interface DbTransfer : UIViewController <DBRestClientDelegate> {

IBOutlet UILabel *fileNameLabel;
IBOutlet UIProgressView *transferProgress;

NSString *srcPath;
NSString *dstPath;

DBRestClient *restClient;


}

@property (nonatomic,retain) IBOutlet UILabel *fileNameLabel;
@property (nonatomic,retain) IBOutlet UIProgressView *transferProgress;
@property (nonatomic,retain) NSString *srcPath;
@property (nonatomic,retain) NSString *dstPath;

- (void) startTransfer;

@end

this is a method inside SecondViewcontroller.m

- (void) startTransfer{
//NSLog(@"%@\n%@",srcPath,dstPath);

if (!fileNameLabel) {
    NSLog(@"null");
}
[self.fileNameLabel setText:[srcPath lastPathComponent]];
//self.fileNameLabel.text=@"test";


NSLog(@"%@",fileNameLabel.text);


restClient = [[DBRestClient alloc] initWithSession:[DBSession sharedSession]];
restClient.delegate=self;

[restClient loadFile:srcPath intoPath:dstPath];

}

as you can see inside the startTransfer I check if fileNameLabel is null and it is, and I don't understand why. Maybe the null value is related to the allocation of the iVar aTransfer. btw it's impossible to set the text of the label.

Answer 1

The problem was in the initialization, i was setting the label before the view was loaded. Initialize the label in viewDidLoad solved the problem.

Answer 2

Elio

Simple test - set a breakpoint at the line where you set self.fileNameLabel.text. When the app stops there, use the debugger to see if the pointer is null.

Most likely causes: - The outlet is not linked properly - The file owner is not of the right class, make sure to set it to your DbTransfer class

H