I have the following code in place:
NSString *mapIDx = #"98";
NSLog(#"map id: %#", mapIDx);
NSFetchRequest *request = [[NSFetchRequest alloc] init];
NSEntityDescription *entity = [NSEntityDescription entityForName:#"WayPoint" inManagedObjectContext:managedObjectContext];
[request setEntity:entity];
//NSPredicate *predicate = [NSPredicate predicateWithFormat:#"waypoint_map_id=%#", mapIDx];
NSPredicate *predicate = [NSPredicate predicateWithFormat:#"waypoint_map_id==%#", mapIDx];
[request setPredicate:predicate];
NSError *error;
listArray = [[managedObjectContext executeFetchRequest:request error:&error] mutableCopy];
[request release];
int arrayItemQuantity = [listArray count];
NSLog(#"Array Quantity: %d", arrayItemQuantity);
// Loop through the array and display the contents.
int i;
for (i = 0; i < arrayItemQuantity; i++)
{
NSLog (#"Element %i = %#", i, [listArray objectAtIndex: i]);
}
/*
NSInteger *xCoordinate = listArray[1];
NSInteger *yCoordinate = listArray[3];
NSLog(#"xCoordinate: %#", xCoordinate);
NSLog(#"yCoordinate: %#", yCoordinate);
CLLocationCoordinate2D coordinate = {xCoordinate, yCoordinate};
MapPin *pin = [[MapPin alloc]initwithCoordinates:coordinate];
[self.mapView addAnnotation:pin];
[pin release];
*/
[listArray release];
As you can see I'm trying to select specific objects from my database, anything with a waypoint_map_id of 98, but the NSPredicate is not working as I expected. Zero objects are getting selected.
Anyone any thoughts ?
The predicate with format does not covert the string "98" to a number. Instead it does
waypoint_map_id == "98"
... which is looking for string attribute. Change the predicate to:
NSInteger mapIdx=98;
NSPredicate *predicate = [NSPredicate predicateWithFormat:#"waypoint_map_id==%d", mapIDx];
... which returns a predicate of:
waypoint_map_id == 98
Assuming that you definately have that object in your database, try adding quotes around the value?
NSPredicate *predicate = [NSPredicate predicateWithFormat:#"waypoint_map_id==\"%#\"", mapIDx];
(clutching at straws!)
Your prediacte looks fine so I would instantly start to suspect the bug is somewhere else :
Is there definintely a waypoint with that id?
Is listArray nil i.e. something else has gone wrong with the request?
You don't check to see what the error is - perhaps that will give you more information?
NSError *error = nil;
NSArray *results = [managedObjectContext executeFetchRequest:request error:&error];
[request release];
if (nil == results || nil != error)
NSLog(#"Error getting results : %#", error);
listArray = [results mutableCopy];
Hope that's helpful at all!
Problem solved:
NSPredicate *predicate = [NSPredicate predicateWithFormat:#"waypoint_map_id contains[cd] %#", mapIDx];
[request setPredicate:predicate];
Related
I want to know how to evaluate NSString which satisfied two conditions using NSPredicate. For example how to check a string that should have atleast one upper case letter and atleast one number.
You can use ANDing for two or more condition.
NSManagedObjectContext *context = [appDelegate managedObjectContext];
NSEntityDescription *entityDescription = [NSEntityDescription entityForName:entityName inManagedObjectContext:context];
NSFetchRequest *fetchRequest = [[NSFetchRequest alloc] init];
[fetchRequest setEntity:entityDescription];
NSPredicate *predicate = [NSPredicate predicateWithFormat:#"fbUID = %# AND birthDate = %d AND birthMonth = %d AND greetingYear = %d", uID, birthDate, birthMonth, greetingYear];
//NSLog(#"%# :",predicate);
[fetchRequest setPredicate:predicate];
NSArray *fetchedObjects = [context executeFetchRequest:fetchRequest error:&error];
You can check more on NSPredicate HERE.
One way to do this is:
NSCharacterSet *upperCaseCharacters = [NSCharacterSet characterSetWithCharactersInString:#"ABCDEFGHIJKLKMNOPQRSTUVWXYZ"];
NSCharacterSet *numbers = [NSCharacterSet characterSetWithCharactersInString:#"0123456789"];
NSPredicate *predicate = [NSPredicate predicateWithBlock:^BOOL(id evaluatedObject, NSDictionary *bindings) {
return ([evaluatedObject rangeOfCharacterFromSet:upperCaseCharacters].location != NSNotFound && [evaluatedObject rangeOfCharacterFromSet:numbers].location != NSNotFound);
}];
NSString *stringToEvaluate = #"aasad5D";
BOOL result = [predicate evaluateWithObject:stringToEvaluate];
Another solution is compound predicate, see this question for example how to use compound predicates create a Compound Predicate in coreData xcode iphone.
I found a solution for this by myself. I used regular expression with predicate to solve this issue.
NSPredicate *pwdCheck = [NSPredicate predicateWithFormat:#"SELF MATCHES %#", #"(?=.*?[A-Z])(?=.*?[0-9]).*"];
bool isValid = [pwdCheck evaluateWithObject:#"99a99A3w"];
Thanks for your help
I have an entity that has 3 attributes: firstname, lastname and score. i am able to search the score of a person by firstname and last name and display it on an UILabel (so far so good) my problem is that i don't know how to update the score attribute with a new value. below the code that i use to perform the search and display the old value.
NSEntityDescription *entitydesc = [NSEntityDescription entityForName:#"Scorecard" inManagedObjectContext:context];
NSFetchRequest *request = [[NSFetchRequest alloc]init];
[request setEntity:entitydesc];
NSPredicate *predicate = [NSPredicate predicateWithFormat:#"firstname like %# and lastname like %#", self.firstnameTextField.text, self.lastnameTextField.text];
[request setPredicate:predicate];
NSError *error;
NSArray *integer = [context executeFetchRequest:request error:&error];
if(integer.count <= 0){
self.displayLabel.text = #"No records found";
}
else {
NSNumber *score;
for (NSManagedObject *object in integer) {
score = [object valueForKey:#"score"];
int x = [score intValue];
// New Value is going to be the old value + 2
int y = x + 2;
//displays old value found
[self.displayLabel setText:[NSString stringWithFormat:#"old value %d",x]];
}
}
update #1
i was able to update the attribute and save it however i had to convert my new Integer value to a string and then convert it back to an integer. i don't like the extra step. if anyone has another suggestion please let me know and thanks for the help. below the updated code.
NSEntityDescription *entitydesc = [NSEntityDescription entityForName:#"Scorecard" inManagedObjectContext:context];
NSFetchRequest *request = [[NSFetchRequest alloc]init];
[request setEntity:entitydesc];
NSPredicate *predicate = [NSPredicate predicateWithFormat:#"firstname like %# and lastname like %#", self.firstnameTextField.text, self.lastnameTextField.text];
[request setPredicate:predicate];
NSError *error;
NSArray *integer = [context executeFetchRequest:request error:&error];
if(integer.count <= 0){
self.displayLabel.text = #"No records found";
}
else {
NSNumber *score;
for (NSManagedObject *object in integer) {
score = [object valueForKey:#"score"];
int x = [score intValue];
int y = x + 2;
NSString* z = [NSString stringWithFormat:#"%d",y];
[object setValue:[NSNumber numberWithInteger:[z integerValue]] forKey:#"score"];
[self.displayLabel setText:[NSString stringWithFormat:#"Value updated to %d",y]];
[context save:&error];
}
}
update 2
Thanks to Kevin's answer I was able to solve my problem. I am now able to replace an integer value from an attribute on my core data with another integer value. below my code finally working.
NSEntityDescription *entitydesc = [NSEntityDescription entityForName:#"Scorecard" inManagedObjectContext:context];
NSFetchRequest *request = [[NSFetchRequest alloc]init];
[request setEntity:entitydesc];
NSPredicate *predicate = [NSPredicate predicateWithFormat:#"firstname like %# and lastname like %#", self.firstnameTextField.text, self.lastnameTextField.text];
[request setPredicate:predicate];
NSError *error;
NSArray *integer = [context executeFetchRequest:request error:&error];
if(integer.count <= 0){
self.displayLabel.text = #"No records found";
}
else {
NSNumber *score;
for (NSManagedObject *object in integer) {
score = [object valueForKey:#"score"];
int x = [score intValue];
int y = x + 2;
[object setValue:[NSNumber numberWithInt:y] forKey:#"score"];
[self.displayLabel setText:[NSString stringWithFormat:#"Value updated to %d",y]];
[context save:&error];
}
}
Get an object like you did before then set's it's score property
[object setValue:[NSNumber numberWithInt:y] forKey:#"score"];
My first suggestion would be to use NSManagedObject's subclasses instead of using primitives. You can do this by using the core data inspector and changing your entity class.
Now, to do a change to the score, you need to find the object you need to change, and assign the value. Once the value is assigned, you will need to save the NSManagedObject the object belongs to. Once the context successfully saves, your changes are persistent.
I am trying to update my local database when app gets response from the web server. When app gets the update from web server, I fetch the data from the local database by matching the id with the response and get one row and perform update code but local database does not get updated and also does not give an error.
What should be the solution???
-(void)checkID:(NSMutableDictionary *)dict
{
NSDictionary *dictEvent = [dict objectForKey:#"Event"];
NSManagedObjectContext *context = [self managedObjectContext];
NSManagedObject *selectedManagedObject = nil;
NSFetchRequest *fetchRequest = [[NSFetchRequest alloc]init];
NSEntityDescription *entity = [NSEntityDescription entityForName:#"Events" inManagedObjectContext:context];
NSSortDescriptor *sortDescObj = [[NSSortDescriptor alloc] initWithKey:#"event_id" ascending:YES];
NSError *error = nil;
NSPredicate *predicate = [NSPredicate predicateWithFormat:[NSString stringWithFormat:#"user_id=%# and event_id=%#",[NSNumber numberWithInt:[[dictEvent valueForKey:#"user_id"] intValue]],[NSNumber numberWithInt:[[dictEvent valueForKey:#"id"] intValue]]]];
NSLog(#"Predicate = %#",predicate);
NSArray *arrSortDescriptors = [NSArray arrayWithObject:sortDescObj];
[fetchRequest setSortDescriptors:arrSortDescriptors];
[fetchRequest setEntity:entity];
[fetchRequest setReturnsDistinctResults:YES];
[fetchRequest setPredicate:predicate];
NSArray *arrResult = [context executeFetchRequest:fetchRequest error:&error];
if ([arrResult count]>0)
{
NSArray *arrKey = [dictEvent allKeys];
NSArray *arrValue = [dictEvent allValues];
NSLog(#"ArrKey : %#\nArrValue : %#",arrKey,arrValue);
selectedManagedObject = [arrResult objectAtIndex:0];
for(int i = 0; i < [arrKey count] ; i++)
{
NSLog(#"selectedMng :- %#",selectedManagedObject);
NSLog(#"KEY: %#\t: %#",[arrKey objectAtIndex:i],[arrValue objectAtIndex:i]);
if ([[arrKey objectAtIndex:i]isEqualToString:#"id"])
{
[selectedManagedObject setValue:[arrValue objectAtIndex:i] forKey:#"event_id"];
}
else if([[arrKey objectAtIndex:i]isEqualToString:#"invited_status"])
{
[selectedManagedObject setValue:[arrValue objectAtIndex:i] forKey:#"invite_status"];
}
else
{
[selectedManagedObject setValue:[arrValue objectAtIndex:i] forKey:[arrKey objectAtIndex:i]];
}
}
if (! [selectedManagedObject.managedObjectContext save:&error])
{
NSLog(#"updateEntityIntoDataBaseNamed - Error :: %#", [error localizedDescription]);
}
// }
}
}
Besides modifying your predicate as suggested by #Martin
NSPredicate *predicate = [NSPredicate predicateWithFormat:#"user_id=%# && event_id=%#",
[NSNumber numberWithInt:[[dictEvent valueForKey:#"user_id"] intValue]],
[NSNumber numberWithInt:[[dictEvent valueForKey:#"id"] intValue]]
];
note that in two cases, you are updating your object using non matching keys: this happens for id and event_id, and for invited_status and invite_status.
You cannot use stringWithFormat within predicateWithFormat. Your predicate should probably look like this:
NSPredicate *predicate = [NSPredicate predicateWithFormat:#"user_id=%# and event_id=%#",
[NSNumber numberWithInt:[[dictEvent valueForKey:#"user_id"] intValue]],
[NSNumber numberWithInt:[[dictEvent valueForKey:#"id"] intValue]]
];
The app needs to retrieve data from core-data then compare one of the values with an IF STATEMENT
MyAppDelegate *appDelegate = [[UIApplication sharedApplication] delegate];
NSManagedObjectContext *context = [appDelegate managedObjectContext];
NSEntityDescription *getDetails = [NSEntityDescription entityForName:#"Detail" inManagedObjectContext:context];
NSFetchRequest *request = [[NSFetchRequest alloc] init];
[request setEntity:getDetails];
NSPredicate *pred = [NSPredicate predicateWithFormat:#"(genID = %i)", genID];
[request setPredicate:pred];
NSSortDescriptor *sort = [[NSSortDescriptor alloc] initWithKey:#"genID" ascending:YES];
[request setSortDescriptors:[NSArray arrayWithObject:sort]];
NSError *error;
NSArray *objects = [context executeFetchRequest:request error:&error];
for (NSManagedObject *oneObject in objects) {
NSString *type = [oneObject valueForKey:#"type"];
if (type == #"straight") {
NSLog(#"straight");
//straight logic removed
}else if (type == #"Left") {
NSLog(#"Left");
//Left logic removed
}else {
NSLog(#"Else");
//Else logic removed
}
}
The issue is that it never goes into "straight" or "left" always the ELSE. Stepping through the code I can see that values do match straight and left, even dumped them into a log file shows them fine. What is wrong?
You need to compare strings using isEqual: or isEqualToString: or compare:.
For instance:
NSString *type = [oneObject valueForKey:#"type"];
if ([type isEqualToString:#"straight"])
// etc.
Search StackOverflow for "NSString equal" or "NSString compare" if you need more explanation. You aren't anywhere near the first person to ask this question, and you definitely won't be the last.
In my application i have a large table of around 20.000 items. I am displaying it on tableview. But the search bar is too slow while doing dynamic search. I have read that NSPredicate method is high performance then NSRange.
I don't know how applicate this method.
My code is :
- (void)filterContentForSearchText:(NSString*)searchText
{
[self.filteredListContent removeAllObjects];
for (Book *book in listContent)
{
NSRange range = [book.name rangeOfString:searchText options:NSCaseInsensitiveSearch];
// is very very slow
if (range.location != NSNotFound)
{
[self.filteredListContent addObject:book];
}
}
}
Where i must insert NSPredicate, into our out the "for"?
- (void)filterContentForSearchText:(NSString*)searchText
{
NSPredicate *predicate = [NSPredicate predicateWithFormat:#"name contains %#", searchText ];
self.filteredListContent = [NSMutableArray arrayWithArray:[listContent filteredArrayUsingPredicate:predicate]];
}
If filtering for instance NSArray, you can use
NSPredicate *predicate = [NSPredicate predicateWithFormat:#"job == 'Programmer'"]
[listOfItems filterUsingPredicate:predicate];
if you want to make a fetch request use
NSFetchRequest *request = [[NSFetchRequest alloc] init];
NSPredicate *predicate = [NSPredicate predicateWithFormat:#"title == %#", aTitle];
[request setEntity:[NSEntityDescription entityForName:#"DVD" inManagedObjectContext:moc]];
[request setPredicate:predicate];
NSError *error = nil;
NSArray *results = [moc executeFetchRequest:request error:&error];
// error handling code
[request release];
EDIT:
ssteinberg's example is simple and good, just one note - you can modify an operator using the key characters c and d within square braces to specify case and diacritic insensitivity respectively. Example [NSPredicate predicateWithFormat:#"name contains[cd] %#", searchString];