How to test if there is an _NSCFConstantString in an NSMutableArray? - ios

Question

Alright, so I have a Popover, containing a tableView, that is populated by an NSMutableArray filled with strings. But there is always one blank/empty string in my NSMutableArray and in turn always an empty cell in my popover table. I've single stepped my project and found that the empty string is a string constant(_NSCFConstantString).
I've tried to get rid of the empty string occurrence by doing a simple empty string test:
[str isEqualToString:#""]
But this doesn't work, I'm assuming because the empty string in my array is of type _NSCFConstantString...?
So what I'm wondering is if there is a way to test if an object is of type _NSCFConstantString, or if you guys have a better way to test if a string is empty...
Here is my full code that pertains to my issue:
NSString *str;
for (int i = 0; i < [self.flattenedDocList count]; i++) {
str = [self.flattenedDocList objectAtIndex:i];
if(![str isKindOfClass:[NSString class]]){
[self.flattenedDocList removeObject: str];
NSLog(#"Just Deleted:%#",str);
}else if([str isEqualToString:#""]){
[self.flattenedDocList removeObject: str];
NSLog(#"Just Deleted:%#",str);
}
}
The first if-statement is a check to get rid of any NSNull objects in my array. Unfortunately this doesn't get rid of the string constants :/
Thank you, any help is greatly appreciated.

Answer 1

Alright, so I made the rookie mistake of modifying an NSMutableArray while enumerating. Also, H2CO3 was right, _NSCFConstantString IS a concrete subclass of NSString, so we can use all NSString methods on them.
Here is a good way to modify an NSMutableArray while enumerating it.
NSMutableArray *tempArray = [[NSMutableArray alloc] initWithArray:self.docList];
self.listForThePopover = [[NSMutableArray alloc] init];
NSString *str;
for (int i = 0; i < [tempArray count]; i++) {
str = [tempArray objectAtIndex:i];
//NSLog(#"~str:%#~",str);
//check if the str is of the NSString class AND if it's NOT empty
if(([str isKindOfClass:[NSString class]]) && (![str isEqualToString:#""])){
//add the string to the list that we want to actually use.
[self.listForThePopover addObject:str];
//NSLog(#"Just Added:%#",str);
}
}

Answer 2

But this does not work, I'm assuming because the empty string in my array is of type _NSCFConstantString...?
Not quite. _NSCFConstantString is a concrete subclass of NSString, so it should work.
Maybe the string is not really and empty string, or it isn't in the array. Check if it's a space (or more of them), by accident. Examine its length property, etc.
By the way, it's a very bad idea to modify a mutable collection while enumerating it, it can lead to logic errors. Maybe that's also part of your current problem in this case.