Getting exc_bad_access in UITableViewController while getting object from NSMutableArray - objective-c

Question

I have a subclass of UITableViewController, and I init the subclass with a NSMutableArray of another custom class:
#import <UIKit/UIKit.h>
#import "NUBCheckpointModel.h"
#interface NUBUserCheckpointModel : NSObject
#property (nonatomic,assign) NSString* objId;
#property (nonatomic,assign) NSString* userId;
#property (nonatomic,assign) NSString* checkpointId;
#property (nonatomic,assign) NSDate* dateAdded;
#property (nonatomic,assign) NUBCheckpointModel* checkpoint;
+ (NUBUserCheckpointModel*) fromJson: (NSString*)json;
#end
This array that is generated from another ViewController, gets passed into this subclassed TableViewController, of which contain this property
#property (nonatomic,retain) NSMutableArray* userCheckpointData;
This property is set like this:
- (id)initWithFrame: (CGRect)frame withType: (TableType)typeOfTable fromParent: (UIViewController*)parent data: (NSMutableArray*)ucpData
{
self = [self init];
if (self) {
self.tableView = [[UITableView alloc] initWithFrame:frame];
self.parentController = parent;
self.userCheckpointData = ucpData;
[self styleTable];
[self addPullToRefreshHeader];
typeCategory = typeOfTable;
}
return self;
}
All is fine up to this part, and any manipulation including trying to get an object from the array works fine. I tested it.
The code I used to test the array is:
NUBUserCheckpointModel* model = [self.userCheckpointData objectAtIndex:0];
NSLog(model.objId);
However, this very same code, when used here:
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
Gives me exc_bad_access. May I know why this happens? I can't seem to figure out why. I'm using ARC btw. Thank you.

Answer 1

While adding the property, you need to take care of the memory management. For string, it is not good practice to set assign property.
Instead , do as following,
#property (nonatomic,copy) NSString* objId;
#property (nonatomic,copy) NSString* userId;
#property (nonatomic,copy) NSString* checkpointId;
#property (nonatomic,retain) NSDate* dateAdded;
#property (nonatomic,retain) NUBCheckpointModel* checkpoint;