Getting SIGABRT error - ios

Question

Am getting a SIGABRT error in main.m:
#import <UIKit/UIKit.h>
#import "AppDelegate.h"
int main(int argc, char * argv[])
{
#autoreleasepool {
return UIApplicationMain(argc, argv, nil, NSStringFromClass([AppDelegate class])); // SIGABRT error
}
}
Am getting this in the console, but can't understand it:
2013-10-24 15:21:30.278 Blog_Reader[45888:a0b] -[__NSDictionaryI length]: unrecognized selector sent to instance 0xb779360
2013-10-24 15:21:30.293 Blog_Reader[45888:a0b] *** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '-[__NSDictionaryI length]: unrecognized selector sent to instance 0xb779360'
*** First throw call stack:
(
0 CoreFoundation 0x017345e4 __exceptionPreprocess + 180
1 libobjc.A.dylib 0x014b78b6 objc_exception_throw + 44
2 CoreFoundation 0x017d1903 -[NSObject(NSObject) doesNotRecognizeSelector:] + 275
3 CoreFoundation 0x0172490b ___forwarding___ + 1019
4 CoreFoundation 0x017244ee _CF_forwarding_prep_0 + 14
5 Foundation 0x010fcb2d -[NSConcreteMutableAttributedString replaceCharactersInRange:withString:] + 39
6 Foundation 0x010fd79a -[NSConcreteMutableAttributedString initWithString:attributes:] + 293
7 UIKit 0x003d7116 -[UILabel _setText:] + 97
8 UIKit 0x003d72d4 -[UILabel setText:] + 40
9 Blog_Reader 0x00002c3d -[TableViewController tableView:cellForRowAtIndexPath:] + 301
10 UIKit 0x00318d2f -[UITableView _createPreparedCellForGlobalRow:withIndexPath:] + 412
11 UIKit 0x00318e03 -[UITableView _createPreparedCellForGlobalRow:] + 69
12 UIKit 0x002fd124 -[UITableView _updateVisibleCellsNow:] + 2378
13 UIKit 0x003105a5 -[UITableView layoutSubviews] + 213
14 UIKit 0x00294dd7 -[UIView(CALayerDelegate) layoutSublayersOfLayer:] + 355
15 libobjc.A.dylib 0x014c981f -[NSObject performSelector:withObject:] + 70
16 QuartzCore 0x03aee72a -[CALayer layoutSublayers] + 148
17 QuartzCore 0x03ae2514 _ZN2CA5Layer16layout_if_neededEPNS_11TransactionE + 380
18 QuartzCore 0x03aee675 -[CALayer layoutIfNeeded] + 160
19 UIKit 0x0034fca3 -[UIViewController window:setupWithInterfaceOrientation:] + 304
20 UIKit 0x0026ed27 -[UIWindow _setRotatableClient:toOrientation:updateStatusBar:duration:force:isRotating:] + 5212
21 UIKit 0x0026d8c6 -[UIWindow _setRotatableClient:toOrientation:updateStatusBar:duration:force:] + 82
22 UIKit 0x0026d798 -[UIWindow _setRotatableViewOrientation:updateStatusBar:duration:force:] + 117
23 UIKit 0x0026d820 -[UIWindow _setRotatableViewOrientation:duration:force:] + 67
24 UIKit 0x0026c8ba __57-[UIWindow _updateToInterfaceOrientation:duration:force:]_block_invoke + 120
25 UIKit 0x0026c81c -[UIWindow _updateToInterfaceOrientation:duration:force:] + 400
26 UIKit 0x0026d573 -[UIWindow setAutorotates:forceUpdateInterfaceOrientation:] + 870
27 UIKit 0x00270b66 -[UIWindow setDelegate:] + 449
28 UIKit 0x00341dc7 -[UIViewController _tryBecomeRootViewControllerInWindow:] + 180
29 UIKit 0x002667cc -[UIWindow addRootViewControllerViewIfPossible] + 609
30 UIKit 0x00266947 -[UIWindow _setHidden:forced:] + 312
31 UIKit 0x00266bdd -[UIWindow _orderFrontWithoutMakingKey] + 49
32 UIKit 0x0027144a -[UIWindow makeKeyAndVisible] + 65
33 Blog_Reader 0x000023bb -[AppDelegate application:didFinishLaunchingWithOptions:] + 267
34 UIKit 0x00223f65 -[UIApplication _handleDelegateCallbacksWithOptions:isSuspended:restoreState:] + 309
35 UIKit 0x002247a5 -[UIApplication _callInitializationDelegatesForURL:payload:suspended:] + 1536
36 UIKit 0x00228fb8 -[UIApplication _runWithURL:payload:launchOrientation:statusBarStyle:statusBarHidden:] + 824
37 UIKit 0x0023d42c -[UIApplication handleEvent:withNewEvent:] + 3447
38 UIKit 0x0023d999 -[UIApplication sendEvent:] + 85
39 UIKit 0x0022ac35 _UIApplicationHandleEvent + 736
40 GraphicsServices 0x036872eb _PurpleEventCallback + 776
41 GraphicsServices 0x03686df6 PurpleEventCallback + 46
42 CoreFoundation 0x016afdd5 __CFRUNLOOP_IS_CALLING_OUT_TO_A_SOURCE1_PERFORM_FUNCTION__ + 53
43 CoreFoundation 0x016afb0b __CFRunLoopDoSource1 + 523
44 CoreFoundation 0x016da7ec __CFRunLoopRun + 2156
45 CoreFoundation 0x016d9b33 CFRunLoopRunSpecific + 467
46 CoreFoundation 0x016d994b CFRunLoopRunInMode + 123
47 UIKit 0x002286ed -[UIApplication _run] + 840
48 UIKit 0x0022a94b UIApplicationMain + 1225
49 Blog_Reader 0x00002e2d main + 141
50 libdyld.dylib 0x01d70725 start + 0
)
libc++abi.dylib: terminating with uncaught exception of type NSException
(lldb)
This is the TableViewController.m file:
#implementation TableViewController
- (void)viewDidLoad
{
[super viewDidLoad];
NSDictionary *blogPost1 = [NSDictionary dictionaryWithObjectsAndKeys:#"The Missing Widget in Android", #"title", #"Ben Jakuben", #"author", nil];
NSDictionary *blogPost2 = [NSDictionary dictionaryWithObjectsAndKeys:#"Getting Started with iOS Development", #"title", #"Amit Bijlani", #"author", nil];
NSDictionary *blogPost3 = [NSDictionary dictionaryWithObjectsAndKeys:#"An Interview with Shay Howe", #"title", #"Joe Villanueva", #"author", nil];
self.blogPosts = [NSArray arrayWithObjects:blogPost1, blogPost2, blogPost3, nil];
}
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
static NSString *CellIdentifier = #"Cell";
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier forIndexPath:indexPath];
// Configure the cell...
cell.textLabel.text = [self.blogPosts objectAtIndex:indexPath.row];
return cell;
}
#end

Answer 1

You are storing NSDictionary instances in self.blogPosts, but then in
cell.textLabel.text = [self.blogPosts objectAtIndex:indexPath.row];
you are assigning one of them to text, which expects a NSString. The compiler is not catching it since objectAtIndex: returns an object of type id, which can potentially be anything.
A possible fix (but it really depends on what you need) could be
cell.textLabel.text = self.blogPosts[indexPath.row][#"title"];