nsarray interview questions
Top nsarray frequently asked interview questions
I'm looking for a method of turning a NSMutableArray into a string. Is there anything on a par with this Ruby array method?
>> array1 = [1, 2, 3]
>> array1.join(',')
=> "1,2,3"
Cheers!
Source: (StackOverflow)
I've got an NSArray and have to iterate over it in a special case backwards, so that I first look at the last element. It's for performance reasons: If the last one just makes no sense, all previous ones can be ignored. So I'd like to break the loop. But that won't work if I iterate forward from 0 to n. I need to go from n to 0. Maybe there is a method or function I don't know about, so I wouldn't have to re-invent the wheel here.
Source: (StackOverflow)
I have a UItableview with reordable rows and the data is in an NSarray. So how do I move an object in the NSMutablearray when the appropriate tableview delegate is called?
Another way to ask this is how to reorder an NSMutableArray?
Source: (StackOverflow)
I have an array with a bunch of strings and I want to check if a certain string is contained in the array. If I use the containsObject: message on the array, I'm getting correct results. Do all NSString objects with the same string point to the same object? Or why is the containsObject: working?
NSArray *stringArray = [NSArray arrayWithObjects:@"1",@"2",@"3",anotherStringValue, nil];
if([stringArray containsObject:@"2"]){
//DO SOMETHING
}
Source: (StackOverflow)
I have an NSArray formed with objects of a custom class. The class has 3 (city, state, zip) string properties. I would like to get all unique state values from the array.
I did read through the NSPredicate class but couldn't make much of how to use it in this case. The only examples I could find were for string operations.
Can someone please help me out?
Source: (StackOverflow)
I am wondering how to convert an NSArray [1,@"Hello",3,4,5] to an string in Objective-C. An Applescript example is:
set the_array to {1,"Two", 3,4,5,6}
set the_array to the_array as string
Source: (StackOverflow)
I have an NSArray of NSNumbers and want to find the maximum value in the array. Is there any built in functionality for doing so? I am using iOS4 GM if that makes any difference.
Source: (StackOverflow)
i am trying to get index of an array through indexOfObject method as follows but when i try to log the value to test the index i get a garbage value.. for testing purposes i am having an array with values {57,56,58..} to get an index of lets say 56,
NSNumber *num = [NSNumber numberWithInteger:56];
NSInteger Aindex = [myArray indexOfObject:num];
NSLog(@" %d",Aindex);
the value i get is something like 2323421. what am i possibly doing wrong??
Source: (StackOverflow)
What I want to do seems pretty simple, but I can't find any answers on the web. I have an NSMutableArray of objects, let's say they are 'Person' objects. I want to sort the NSMutableArray by Person.birthDate which is an NSDate.
I think it has something to do with this method:
NSArray *sortedArray = [drinkDetails sortedArrayUsingSelector:@selector(???)];
In Java I would make my object implement Comparable, or use Collections.sort with an inline custom comparator...how on earth do you do this in Objective-C?
Source: (StackOverflow)
I'm looking for the standard idiom to iterate over an NSArray. My code needs to be suitable for OS X 10.4+.
Source: (StackOverflow)
I need to reverse my NSArray.
As an example:
[1,2,3,4,5] must become: [5,4,3,2,1]
What is the best way to achieve this?
Source: (StackOverflow)
I am new to Core Data. I have noticed that collection types are not available as attribute types and would like to know what the most efficient way is of storing array/dictionary type data as an attribute (e.g. the elements that make up an address like street, city, etc. does not require a separate entity and is more conveniently stored as a dictionary/array than separate attributes/fields). Thank you.
Source: (StackOverflow)
I'm able to put the contents of an NSSet into an NSMutableArray like this:
NSMutableArray *array = [set allObjects];
The compiler complains though because [set allObjects] returns an NSArray not an NSMutableArray. How should this be fixed?
Source: (StackOverflow)