Getting only one value when appending NSString to NSArray - ios

Question

Below is my code. When Looping over an NSArray of NSDictionary objects and trying to append to an array I keeping an NSLog which shows the correct result, but the result NSArray only contains the last record.
for (NSDictionary *entry in entries) {
NSString* projID = [entry objectForKey:#"NM_PROJECT"];
NSArray *projectNames = [[NSArray alloc] initWithObjects:projID,nil];
_projectpicker.delegate = self;
_projectpicker.dataSource = self;
NSLog(#"Error : %#", projID);
}
Log Result:
Test1
test2
test3
test4
When appending to NSArray (Projectnames) I was getting last data..

Answer 1

Every each loop iteration you initialise new array, you don't add new object to the array.
To do that you have to create NSMutableArray before loop and add object inside loop:
NSMutableArray *projectNames = [[NSMutableArray alloc] init];
for (NSDictionary *entry in entries) {
NSString* projID = [entry objectForKey:#"NM_PROJECT"];
[projectNames addObject: projID];
_projectpicker.delegate = self;
_projectpicker.dataSource = self;
NSLog(#"Error : %#", projID);
}
NSLog(#"Array : %#", projectNames);

Answer 2

Keep alloc statement outside of your for loop and use a NSMutableArray and then keep on adding to this array as and when required from inside the for loop.
NSMutableArray *projectNames = [[NSMutableArray alloc] init];
for(...)
{
[projectNames addObject: anyObject];
}

Answer 3

Setting:
_projectpicker.delegate = self;
_projectpicker.dataSource = self;
inside a loop doesn't make much sense. You don't need to do it multiple times.
While the other answers accurately describe what you're doing wrong with the array, your current requirement can be achieved more succinctly using KVC:
NSArray *projectNames = [entries valueForKey:#"NM_PROJECT"];
(then you don't need your own loop at all)