try this:
-(NSMutableArray *)lijstArray{
if(!_lijstArray){ //If you need get new lijstArray always, comment this line, and below "}"
NSString *lijstString = self.details[@"lijst"];
NSArray *tempArray = [lijstString componentsSeparatedByString:@", "];
_lijstArray = [NSMutableArray array];
for (NSString *lijstValue in tempArray) {
[_lijstArray addObject:[lijstValue stringByTrimmingCharactersInSet:[NSCharacterSet whitespaceAndNewlineCharacterSet]]];
}
}
return _lijstArray;
}