UITableView application crashes when scrolling - iphone

Question

Firstly, please forgive my English.
I am learning about iPhone SDK, Obj-C and trying to make UITableView app. But my app crashes when scrolling the table. I've searched but can't solve my problem, so I post my question here and look for your help.
TMTMemberListTableViewController.h
#interface TMTMemberListTableViewController : UITableViewController
{
NSMutableArray *familyMembers;
sqlite3 *database;
}
#property (nonatomic, retain) NSMutableArray *familyMembers;
- (void) configureCell:(TMTFamilyMemberCell *)cell withFamilyMember:(TMTFamily *)member;
#end
TMTMemberListTableViewController.m
#interface TMTMemberListTableViewController (Private)
- (void) loadMemberListFromDatabase;
#end
#implementation TMTMemberListTableViewController
#synthesize familyMembers;
- (void) loadMemberListFromDatabase
{
familyMembers = [[NSMutableArray alloc] init];
NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
NSString *documentsDirectory = [paths objectAtIndex:0];
NSString *path = [documentsDirectory stringByAppendingPathComponent:#"easycook.sqlite"];
if (sqlite3_open([path UTF8String], &database) == SQLITE_OK)
{
const char *sql = "SELECT member_id from family";
sqlite3_stmt *statement;
if (sqlite3_prepare_v2(database, sql, -1, &statement, NULL) == SQLITE_OK)
{
while (sqlite3_step(statement) == SQLITE_ROW)
{
NSString *memberID = [NSString stringWithUTF8String:(char *) sqlite3_column_text(statement, 0)];
TMTFamily *member = [[TMTFamily alloc] initWithMemberID:memberID database:database];
[familyMembers addObject:member];
[member release];
}
}
sqlite3_finalize(statement);
}
else
{
sqlite3_close(database);
NSAssert1(0, #"Failed to open database with message '%s'.", sqlite3_errmsg(database));
}
}
- (void)viewDidLoad
{
[super viewDidLoad];
self.clearsSelectionOnViewWillAppear = NO;
self.navigationItem.rightBarButtonItem = self.editButtonItem;
[self loadMemberListFromDatabase];
}
- (void)didReceiveMemoryWarning
{
[super didReceiveMemoryWarning];
// Dispose of any resources that can be recreated.
}
- (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView
{
// Return the number of sections.
return 1;
}
- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section
{
// Return the number of rows in the section.
return [familyMembers count];
}
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
//static NSString *MyIdentifier = #"MyIdentifier";
TMTFamilyMemberCell *cell = (TMTFamilyMemberCell *)[tableView dequeueReusableCellWithIdentifier:nil];
if (cell == nil)
{
cell = [[[TMTFamilyMemberCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:nil] autorelease];
cell.accessoryType = UITableViewCellAccessoryDisclosureIndicator;
}
TMTFamily *member = [familyMembers objectAtIndex:indexPath.row];
// Set up the cell
[self configureCell:cell withFamilyMember:member];
[member release];
return cell;
}
- (void) configureCell:(TMTFamilyMemberCell *)cell withFamilyMember:(TMTFamily *)member
{
cell.familyMember = member;
cell.memberNameLabel.text = member.description;
}
- (void)dealloc
{
NSLog(#"Dealloc");
[familyMembers release];
[super dealloc];
}
When scrolling table, my app crashes with EXC_BAD_ACCESS at
[self configureCell:cell withFamilyMember:member];
and
cell.memberNameLabel.text = member.description;

Answer 1

This line is not incrementing retain counter:
TMTFamily *member = [familyMembers objectAtIndex:indexPath.row]
So the following line is your problem
[member release];
You cannot release object if you down't own it. Either retain it like that:
TMTFamily *member = [[familyMembers objectAtIndex:indexPath.row] retain];
or
TMTFamily *member = [[familyMembers objectAtIndex:indexPath.row] copy];
or remove mentioned release completelly.

Answer 2

First off, welcome to Stack Overflow and welcome to the world of iOS Development.
There are a bunch of problems with your code and if you have an Apple developer account, I highly suggest you head over to the 2012 WWDC Session Videos and look at the talk about Modern Objective C session. https://developer.apple.com/videos/wwdc/2012/
Looking at the code, your bad access could either be an already released object or an empty cell. To determine the cause, you need to enable NSZombies. To do so, click on your project name in the tool bar as shown here:
In this example, it's called PartialTransparentcy (spelling be damned). When you click that button, click the edit scheme button and you'lll see a list of options. You'll want to click enable Zombie objects. If you don't see it, press the Diagnostics tab.
Then run your code and it'll log the object that is giving your grief. Just remember that zombie objects are very expensive. If you submit an app with them enabled, you'll be automatically rejected.
The first thing I notice when I look at your cell initialization code is this:
TMTFamilyMemberCell *cell = (TMTFamilyMemberCell *)[tableView dequeueReusableCellWithIdentifier:nil];
You are sending in a nil identifier which negates that whole entire point of reusing cells. Instead, you are creating a new cell for each row instead of reusing older cells.
So uncomment this line:
static NSString *MyIdentifier = #"MyIdentifier";
and change the dequeue method to read like this:
TMTFamilyMemberCell *cell = (TMTFamilyMemberCell *)[tableView dequeueReusableCellWithIdentifier:MyIdentifier];
If you are building your cell in interface builder, you'll need to also give the cell an identifier. This may be the cause of the crash.
Next ... your sqllite code should be encapsulated in another object. There's no reason for the view controller to know about it. Also, you should really investigate core data. It defaults to sqllite backing store. It's also a pretty awesome technology.
And finally, take a look at ARC. Let the compiler handle the grunt work of memory management so that you can focus on the user experience of your application.
Hope that helps and good luck!