NSMutableDictionary *dic0 = [[NSMutableDictionary alloc] initWithObjectsAndKeys:#"string0", #"key0", nil];
NSDictionary *dic1 = [[NSDictionary alloc] initWithObjectsAndKeys:#"string1", #"key1", nil];
NSDictionary *dic2 = [[NSDictionary alloc] initWithObjectsAndKeys:#"string2", #"key2", nil];
NSDictionary *dic3 = [[NSDictionary alloc] initWithObjectsAndKeys:#"dic3", #"key3", nil];
NSArray *arrayOri = [[NSArray alloc] initWithObjects:dic0, dic1, dic2, nil];
//here means a deep copy
NSMutableArray *arrayDeepCopy = [[NSMutableArray alloc] initWithArray:arrayOri copyItems:YES];
NSRange range = {0, 2};
NSArray *subArray = [arrayOri subarrayWithRange:range];
[arrayDeepCopy addObject:dic3];
NSLog(#"arrayOri not merge %#", arrayOri);
//merge one object
[dic0 setObject:#"mutableV" forKey:#"mutableKey"];
//dealloc one object
[dic1 dealloc];
NSLog(#"arrayOri %# ", arrayOri);
NSLog(#"subArray %# ", subArray);
crash here,because of dic1 dealloced,if deep copy,why the original object has an effect with new object??
NSLog(#"array %# ", arrayDeepCopy);
what initWithArray:(NSArray *)array copyItems:(BOOL)flag do after all??
The problem is that dic1 is an immutable object. Thus is does not make sense to copy it in memory, and therefore arrayDeepCopy holds a pointer to the original dic1 object. When you deallocate it, it is gone from all arrays that store it.
If you want to have a true deep copy, you have to instantiate a NSMutableDictionary.
Related
I want to store data from a text field. And then use this data to populate the text in a label inside a view controller. Is this possible? Ive messed around with it, but nothing seems to work. Any thoughts? Here are my two methods...
- (IBAction)saveButton:(id)sender {
CoreDataStack *coreDataStack = [CoreDataStack defaultStack];
NSManagedObject *noteEntry = [NSEntityDescription insertNewObjectForEntityForName:#"Notes" inManagedObjectContext:coreDataStack.managedObjectContext];
[noteEntry setValue:_notesField.text forKey:#"notes"];
NSError *error = nil;
// Save the object to persistent store
if (![coreDataStack.managedObjectContext save:&error]) {
NSLog(#"Can't Save! %# %#", error, [error localizedDescription]);
}
[coreDataStack saveContext];
}
Here is my view did load method:
- (void)viewDidLoad
{
[super viewDidLoad];
CoreDataStack *coreDataStack = [CoreDataStack defaultStack];
NSFetchRequest *request = [[NSFetchRequest alloc] initWithEntityName:#"Notes"];
Notes *entry = [NSEntityDescription insertNewObjectForEntityForName:#"Notes" inManagedObjectContext:coreDataStack.managedObjectContext];
_outputLabel.text = entry.notes;
}
Your code in the saveButton: method seems OK. But your code in the viewDidLoad method seems wrong. Are you trying to do the following?
- (void)viewDidLoad {
[super viewDidLoad];
CoreDataStack *coreDataStack = [CoreDataStack defaultStack];
//First way to init your fetchRequest:
NSFetchRequest *request = [[NSFetchRequest alloc] initWithEntityName:#"Notes"];
//Second way to init your fetchRequest:
NSFetchRequest *request = [[NSFetchRequest alloc] init];
NSEntityDescription *entity = [NSEntityDescription entityForName:#"Notes" inManagedObjectContext:coreDataStack];
[fetchRequest setEntity:entity];
//Having a NSEntityDescription object can be usefull if you need to group your data, for example
//Set some predicates, if necessary
//Set some sortdescriptors, if necessary
NSError *error;
NSArray *resultsArray = [coreDataStack executeFetchRequest:request error:&error];
NSLog(#"%#", resultsArray);
_outputLabel.text = [[resultsArray firstObject] notes]; //if your array can only have one object
}
The NSLog will give you the structure of your fetch array (I can't guess it). You will then be able to set _outputLabel.text.
Answer by #user1966109 is exactly correct answer what you are looking for. Since you need to show the text in a label and for that you need to set predicate to get a single row. Set the predicate as below
NSPredicate *predicate = [NSPredicate predicateWithFormat:#"value == abc"];//considerin abc is the word you are looking for.
request.predicate = predicate;
//then execute the query.
How does one fetch a set of unique managed objects by requesting a specific attribute to be checked.
e.g. A number of people objects and I would like to retrieve all the unique names, one managed object for each unique name, sorted by name.
What about using a request like this
NSFetchRequest *request = [[NSFetchRequest alloc] init];
NSEntityDescription *entity = [NSEntityDescription entityForName:#"Person" inManagedObjectContext:managedObjectContext];
request.entity = entity;
request.propertiesToFetch = [NSArray arrayWithObject:[[entity propertiesByName] objectForKey:#"name"]];
request.returnsDistinctResults = YES;
request.resultType = NSDictionaryResultType;
NSSortDescriptor *sortDescriptor = [[NSSortDescriptor alloc] initWithKey:#"name" ascending:YES];
[request setSortDescriptors:[NSArray arrayWithObject:sortDescriptors]];
NSError *error = nil;
NSArray *distinctResults = [managedObjectContext executeFetchRequest:request error:&error];
// Use distinctResults
Try and let me know.
P.S. Code is ARC enabled. If you are not using it, call release when necessary.
I have been trying to add an object as an NSMutableDictionary to my array, which I am accessing from another view, and It doesn't seem to work. I want to be able to store the data in a plist which I access from a NSDictionary.
-(void)saveAlarm:(id)sender {
// Adding object for alarm to AlarmViewController
alarmArrayCopy = alarmViewController.alarmsTime;
NSMutableDictionary *newAlarm = [[NSMutableDictionary alloc] init];
[newAlarm setValue:labelTextField.text forKey:LABEL_KEY];
[newAlarm setValue:alarmPicker.date forKey:TIME_KEY];
[alarmArrayCopy addObject:(newAlarm)];
// Dismissing and tiding up.
[self.navigationController dismissModalViewControllerAnimated:YES];
[newAlarm release];
}
UPDATE: How do I add an NSDictionary to my plist database (my db is an array)?
Here is some new code, I updated the NSMutableDictionary to NSDictionary because in my plist you can only have normal dictionaries not a mutable one. But now it crashed and gives me a Thread 1:Program received signal: "SIGABRT".
NSString *path = [[NSBundle mainBundle] bundlePath];
NSString *finalPath = [path stringByAppendingPathComponent:#"data.plist"];
// Adding object for alarm to AlarmViewController
NSDictionary *newAlarm = [[NSDictionary alloc] init];
[newAlarm setValue:labelTextField.text forKey:LABEL_KEY];
[newAlarm setValue:[NSString stringWithFormat:#"%#", alarmPicker.date] forKey:TIME_KEY];
[newAlarm writeToFile:finalPath atomically:NO];
or
-(IBAction)saveAlarm:(id)sender {
// Adding object for alarm to AlarmViewController
NSString *time = [NSString stringWithFormat:#"%#", alarmPicker.date];
NSString *label = [NSString stringWithFormat:#"%#",labelTextField.text];
NSDictionary *newAlarm = [[NSDictionary alloc] initWithObjectsAndKeys:label, LABEL_KEY,time, TIME_KEY, nil];
self.alarmArrayCopy = alarmViewController.alarmsTime;
[alarmArrayCopy addObject:(newAlarm)];
// Dismissing and tiding up.
[newAlarm release];
[self.navigationController dismissModalViewControllerAnimated:YES];
}
First, you should use setObject:forKey: method for adding objects to NSMutableDictionary. Second, you should use initWithObjectsAndKeys: method if you are using NSDictionary.
The setValue:forKey is a method of the Key Value Coding protocol. That was described at here “
Where's the difference between setObject:forKey: and setValue:forKey: in NSMutableDictionary?
”
So, you should do that,
NSDictionary *newAlarm = [[NSDictionary alloc] initWithObjectsAndKeys:
labelTextField.text, LABEL_KEY,
alarmPicker.date, TIME_KEY, nil];
[newAlarm setValue:alarmPicker.date forKey:TIME_KEY];
I am not quite sure, but I guess your error is because you can't send an instance of NSDate object to setValue:forKey method. You may use either setObject:forKey or change NSDate to NSString by [NSString stringWithFormat:"%#", alarmPicker.date].
Hope that helps.
In my code, i'm creating 5 sets of objects, and 5 NSArrays containing those objects. At the end of my method, two of the arrays release properly, but the other three crash my application.
Creating
UIImageView *image0 = [[UIImageView alloc] initWithImage:[UIImage imageNamed:#"TankAxe.png"]];
NSArray *imageArray = [[NSArray alloc] initWithObjects:image0, nil];
NSString *name0 = [NSString stringWithString:#"Pistol"];
NSArray *nameArray = [[NSArray alloc] initWithObjects:name0, nil];
NSNumber *price0 = [NSNumber numberWithInt:100];
NSArray *priceArray = [[NSArray alloc] initWithObjects:price0, nil];
NSNumber *round0 = [NSNumber numberWithInt:0];
NSArray *roundArray = [[NSArray alloc] initWithObjects:round0, nil];
NSNumber *priceRound0 = [NSNumber numberWithInt:0];
NSArray *priceRoundArray = [[NSArray alloc] initWithObjects:priceRound0, nil];
Releasing
[name0 release];
[nameArray release]; //Releases properly
[image0 release];
[imageArray release]; //Releases properly
[price0 release];
NSLog(#"%i",[priceArray retainCount]); //Returns 1
[priceArray release]; //Source of the crash
[round0 release];
[roundArray release]; //Also crashes
[priceRound0 release];
[priceRoundArray release]; //Also Crashes
Anybody know how to properly release the arrays containing NSNumbers?
price0, name0,round0, and priceRound0 should not be released. They were not created with alloc, and will be autoreleased by the methods that returned them.
Once you release an object that you shouldn't, the heap is corrupted, and the program could crash at any time.
The easiest way to debug this is to turn on zombies (Tip #1):
http://www.loufranco.com/blog/files/debugging-memory-iphone.html
I have an entity ("Settings") and I want to get all the values in just one field ("Status").I am using coredata. Can anyone help me, please?
Declare this in .h file:
NSMutableArray *eventArray;
and in .m file
- (void)fetchRecords {
// Setup the fetch request
NSFetchRequest *fetchRequest = [[NSFetchRequest alloc] init];
// Define our table/entity to use
NSEntityDescription *entity = [NSEntityDescription entityForName:#"Settings" inManagedObjectContext:managedObjectContext];
NSSortDescriptor *sortDescriptor = [[NSSortDescriptor alloc] initWithKey:#"Status" ascending:YES];
NSArray *sortDescriptors = [[NSArray alloc] initWithObjects:sortDescriptor, nil];
[fetchRequest setSortDescriptors:sortDescriptors];
[fetchRequest setEntity:entity];
[fetchRequest setEntity:entity];
NSError *error;
// Get array of results.
NSMutableArray *theResults = [[managedObjectContext executeFetchRequest:fetchRequest error:&error] mutableCopy];
if (!theResults) {
// Handle the error.
// This is a serious error and should advise the user to restart the application
}
// Grab unique neighborhoods through NSSet.
NSSet *uniqueElements = [NSSet setWithArray:[theResults valueForKey:#"Status"]];
// Dump NSSet uniques into new array.
NSMutableArray *sortedResults = [[NSMutableArray alloc] initWithArray:[uniqueElements allObjects]];
for(int i = 0; i < [sortedResults count];i++)
{
NSLog(#"%d. %#", i+1, [sortedResults objectAtIndex:i]);
}
// Save our fetched data to an array
[self setEventArray: sortedResults];
}
At first, u can get Array of values:
NSFetchRequest *requestSettings = [[NSFetchRequest alloc] init];
[requestCodesList setEntity:[NSEntityDescription entityForName:#"Setting" inManagedObjectContext:managedObjectContext]];
NSArray *setting = [managedObjectContext executeFetchRequest:requestCodesList error:&error];
if (error) NSLog(#"Failed to executeFetchRequest to data store: %#", [error localizedDescription]);
Next, u transfer u array in NSString:
ComponentsJoinedByString: Constructs
and returns an NSString object that is
the result of interposing a given
separator between the elements of the
array.
(NSString *)componentsJoinedByString:(NSString *)separator
code is:
NSString *settingChanged = [setting componentsJoinedByString:#","];
And after u can using this anywhere in u UI (binding, setStringValue e.t.c)