My question is how to pass Null values in to NSMutableArray/NSArray.
But by searching google and going through different sites, i think that i have achieved my purpose. But, while trying i got a new doubt.
See the below code to understand my question
I am declaring a mutable array and initializing it with some objects initially and also i am passing a null in to it at the time of declaration itself.
Now when i run this code below
NSMutableArray * mar = [[NSMutableArray alloc]initWithObjects:@"first",@"last", nil];
[ar addObject:[NSNull null]];
NSLog(@"%@",mar);
The o/p is :
(
first,
last,
"<null>"
)
But my actual doubt is when i initialize the NSMutableArray as below
NSString *str;
NSMutableArray * mar = [[NSMutableArray alloc]initWithObjects:@"first",str,@"last", nil];
[ar addObject:[NSNull null]];
NSLog(@"%@",mar);
The o/p is :
(
first,
"<null>"
)
The 2nd element in the array is "null", i understand that as i have passed a variable without assigning any value to it. It is printing null. But why are the remaining elements not printed.
According to what i know, the array will stop adding elements whenever it overcomes nil while initializing. But here, in this case. The o/p shows that the 2nd element is also null.(But not nil.)
Then why does the remaining elements are not printed.
UPDATING QUESTION
NSString* str;
NSLog(@"%@",str);
NSMutableArray * mar = [[NSMutableArray alloc]initWithObjects:@"first",str,@"last", nil];
NSLog(@"%@",mar);
and the o/p for the above code is
(null) // for str an uninitialised NSString variable.
(
first // first element in the array
)
If the value present in str is (null), how come the array encountered nil and stopped adding elements to array and printing them.
Now, someone answer this?
initWithObjects uses nil as the marker for the last item. If you pass a nil (the unitialized str variable) to it as the 2nd item out of 4, only the first one is actually added.
[[NSMutableArray alloc]initWithObjects:@"first",str ?: [NSNull null],@"last", nil];
will fix your problem by replacing the nil with a [NSNull null].