Can't see view controller content after pushing to table view controller - ios

Question

I'm new i iOS and Objective-C world, I want to create an example app to learn something but i find some problems in my program.
I Create a TableViewController with Books names, and after touch a book I want see a some more inforamtion about this book.
So I created book class what is a view controller, i created a some Labels inside this class with some text.
NSLogs works fine. After touch the record, apps pushing to new view controller from table view controller worsk good, but I can't see any content over there instead of white bg and back button at the top.
this is book class:
#import "BooksViewController.h"
#interface BooksViewController ()
#end
#implementation BooksViewController
- (id) initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil
{
if(self){
self.title = self.bookName;
self.view.backgroundColor = [UIColor whiteColor];
}
return self;
}
- (void)viewDidLoad {
[super viewDidLoad];
UILabel *bookNameLabel = [[UILabel alloc] init];
bookNameLabel.text = self.bookName;
bookNameLabel.frame = CGRectMake(10, 10, 300, 50);
[self.view addSubview:bookNameLabel];
UILabel *authorNameLabel = [[UILabel alloc] init];
authorNameLabel.text = self.authorName;
authorNameLabel.frame = CGRectMake(50, 50, 300, 40);
[self.view addSubview:authorNameLabel];
UILabel *bookDescLabel = [[UILabel alloc] init];
bookDescLabel.text = self.bookDesc;
bookDescLabel.frame = CGRectMake(50, 50, 300, 40);
[self.view addSubview:bookDescLabel];
}
- (void)didReceiveMemoryWarning {
[super didReceiveMemoryWarning];
// Dispose of any resources that can be recreated.
}
#end
this is a methods in table view controller witch I use to create a books inforamtion window:
- (void)viewDidLoad {
[super viewDidLoad];
self.bookNames = #[#"Pan Tadeusz", #"Potop", #"Lalka", #"Uczta dla wron", #"Symfonnia C++"];
self.authorsName = #[#"Adam Mickiewicz", #"Henryk Sienkiewicz", #"Bolesław Prus", #"George R.R Martin", #"Jerzy Greborz"];
self.bookDescs = #[#"Opis Pan Tadeusz", #"Opis Potop", #"Opis Lalka", #"Opis Uczta dla wron", #"Opis Symfonnia C++"];
}
-(void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath
{
NSLog(#"Książka na pozycji %ld tapped",indexPath.row);
BooksViewController *bookVC = [[BooksViewController alloc] init];
bookVC.bookName = self.bookNames[indexPath.row];
bookVC.authorName = self.authorsName[indexPath.row];
bookVC.bookDesc = self.bookDescs[indexPath.row];
NSLog(#"Nazwa wybranej książki: %#",bookVC.bookName);
[self.navigationController pushViewController:bookVC animated:YES];
}

Answer 1

You're doing this wrong.
First, create an iVar that will save the Indexpath that the user selected, for that, simply add an NSIndexPath variable at the very top of your .m file.
#implementation yourControllerNameHere (){ //In your code you will have your controller name, just add the NSIndexpath ;)
NSIndexPath *selectedPath;
}
You then need to perform a segue when you select a tableview cell, for that, replace your -didSelectRowAtIndexPath method with this :
-(void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath
{
NSLog(#"Książka na pozycji %ld tapped",indexPath.row);
selectedPath = indexPath; //We're saving the selected path to our instance variable ! This is very important otherwise we can't find it again.
[self performSegueWithIdentifier:#"fromBooksToDetail"];
}
and add the -prepareForSegue method in your .m file ; it should be there when you first created it ! just find it and add the following
- (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender {
if([segue.identifier isEqualToString:#"fromBooksToDetail"]){
BooksViewController *bookVC =(BooksViewController*)segue.destinationViewController;
bookVC.bookName = self.bookNames[selectedPath.row];
bookVC.authorName = self.authorsName[selectedPath.row];
bookVC.bookDesc = self.bookDescs[selectedPath.row];
NSLog(#"Nazwa wybranej książki: %#",bookVC.bookName);
}
}
Now this will NOT work unless you add a segue link between your two viewcontrollers in storyboard, so simply open your storyboard and, using a right clic or a ctrl+left clic, drag your mouse from your TableViewController to your BooksController. Don't forget to give it the right identifier in the Attributes Inspector on the right panel !
Note that I wouldn't have named them like that ; BooksViewController has more sense if it's the TableViewController name, and "BookDetailViewController" for the detail page. But that's just a detail.
Once you have the segue link, the performSegue call and the prepareForSegue method, you'll be all set ;)

Answer 2

You need to learn how to debug. Try putting NSLog(#"bookname: %#", self.bookName) in your viewDidLoad and see if you print anything. (Most probably not)
I'm not 100% sure how the view life cycle works when you use alloc init for a view controller. But my bet is that the properties are not set there. Try moving bookNameLabel.text = self.bookName; to viewWillAppear instead of viewDidLoad
You should use storyboards instead. It's super easy.
Also, your initWithNibName will never get called. You are using the init-method.