Question

Right now I’m taking my NSDictionary and running a loop of all values to find the low, high, and calculate average.

Since I’m new to IOS I wanted to ask if there is a better way to do this. Is there? Thanks.

Answer 1

The exact answer to this question depends on what type of objects are in your NSDictionary. The answer in general is that you can probably use Key-Value Coding operators to do what you want. Here is an example:

NSNumber *one = [NSNumber numberWithInt:1];
NSNumber *two = [NSNumber numberWithInt:2];
NSNumber *three = [NSNumber numberWithInt:3];

NSDictionary *dictionary = [NSDictionary dictionaryWithObjectsAndKeys:one, @"apple", two, @"orange", three, @"pear", nil];
NSLog(@"The max number is %@", [[dictionary allValues] valueForKeyPath:@"@max.intValue"]);
NSLog(@"The min number is %@", [[dictionary allValues] valueForKeyPath:@"@min.intValue"]);
NSLog(@"The mean is %@", [[dictionary allValues] valueForKeyPath:@"@avg.intValue"]);

This is probably no more efficient than enumerating things yourself, but it is more concise.

If the contents of your NSDictionary are objects of a custom class that have an NSNumber as a property, you can still use this method by placing the property name after the @avg, e.g. @avg.myProperty. Note that these valueForKeyPath methods return NSNumbers.