Not able to display results in the console - ios

Question

I made an application for storing data in CD. I want to just simply write the things into the console but I can't get printed on the console. Am I doing something wrong?
Here is my code whole demo application.
Here is my screen shot of Core_Data_Demo_xcdatamodeld
// AppDelegate.h
#import <UIKit/UIKit.h>
#import <CoreData/CoreData.h>
#interface AppDelegate : UIResponder <UIApplicationDelegate>
#property (strong, nonatomic) UIWindow *window;
#property (readonly, strong, nonatomic) NSManagedObjectContext *managedObjectContext;
#property (readonly, strong, nonatomic) NSManagedObjectModel *managedObjectModel;
#property (readonly, strong, nonatomic) NSPersistentStoreCoordinator *persistentStoreCoordinator;
- (void)saveContext;
- (NSURL *)applicationDocumentsDirectory;
#end
// AppDelegate.h
-(BOOL)createNewRectangleWithHeight:(NSInteger)heightParam width:(NSInteger)widthParam{
if (heightParam ==0 || widthParam ==0) {
NSLog(#"The height and width must no be 0");
return NO;
}
Rectangle *rect = [NSEntityDescription insertNewObjectForEntityForName:#"Rectangle" inManagedObjectContext:self.managedObjectContext];
if (rect == nil) {
NSLog(#"Failed to create new Rectangle");
return NO;
}
rect.height = [NSNumber numberWithInt:heightParam];
rect.width = [NSNumber numberWithInt:widthParam];
NSError *savingError = nil;
if ([self.managedObjectContext save:&savingError]) {
return YES;
} else {
NSLog(#"Failed to save new person. Error = %# ",savingError);
}
return YES;
}
- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {
[self createNewRectangleWithHeight:2 width:2];
return YES;
}

Answer 1

You are not able to see any statements because (I suppose) things run correctly.
If you want to retrieve data and print in the console you need to run a different method like printData or whatever you want. This method should set up a NSFetchRequest and execute it against your entity Rectangle.
- (void)printData {
NSFetchRequest *request = [NSFetchRequest fetchRequestWithEntityName:#"Rectangle"];
NSError *error = nil;
NSArray *results = [self.managedObjectContext executeFetchRequest:request error:&error];
if(error) {
// An error occurred
} else {
// See the results
}
}
Usage
- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {
// [self createNewRectangleWithHeight:2 width:2];
[self printData];
return YES;
}
You should comment the createNew... method otherwise you will see multiple entries (equal to the number of times you've run the application) of Rectangle objects with the same width and height.

Answer 2

The code which you have shown is for adding values using core data, If you do not get any error in the NSError object while you are adding the values then data is successfully added inside the sqlite file.
To check the added values what you can do is use the SqliteManager addon from firefox and open the sqlite file (You can get the sqlite file location using NSHomeDirectory() method for it and then jump to the documents folder).
If you don't want the addon way you can always use NSFetchRequest to pull your data given below is the code for the same
- (NSManagedObjectContext*)getManagedObjectContext{
AppDelegate *appDelegate = (AppDelegate*)[UIApplication sharedApplication].delegate;
return appDelegate.managedObjectContext;
}
- (void)fetchdataFromDatabase{
NSManagedObjectContext *appContext = [self getManagedObjectContext];
if(appContext!=nil){
NSFetchRequest *fetchRequest = [[NSFetchRequest alloc] init];
NSEntityDescription *entity = [NSEntityDescription entityForName:#"YOUR_ENTITY_NAME" inManagedObjectContext:appContext];
[fetchRequest setEntity:entity];
NSError *error = nil;
NSArray *fetchedObjects = [appContext executeFetchRequest:fetchRequest
error:&error];
if(error!=nil && fetchedObjects.count!=0){
// print your data here
}else{
//Print the error here
}
}
}