Question

I used NSNumber class.

but methods that can use is different in follow environments.

First is a picture in command line tool environment. (Mac os x)

Second is a picture in single view application environment. (iOS)

: Can’t use isGreaterThan:, isGreaterThanOrEqualTo:, isLessThan:.. Etc. methods

Why did that?

1] first picture

2] second picture

Answer 1

Those methods you’re seeing on the Mac aren’t actually part of the NSNumber class but instead are part of an informal protocol called NSComparisonMethods that is only available on Mac OS X. The methods in this protocol are convenience methods that actually just use the compare: method already available on many Cocoa classes. If you wanted, you could implement these methods as a category on NSNumber quite easily. Here is how I would implement -isGreaterThanOrEqualTo:.

@interface NSNumber (ConvenientComparison)

- (BOOL)isGreaterThanOrEqualTo:(id)object;

@end

@implementation NSNumber (ConvenientComparison)

- (BOOL)isGreaterThanOrEqualTo:(id)object
{
    if (![object isKindOfClass:[NSNumber class]])
    {
        // Not sure what NSNumber does if you pass in something that isn't a number.
        // Handle this case
        return NO;
    }

    NSNumber *numberToCompareAgainst = (NSNumber *)object;

    NSComparisonResult comparisonResult = [self compare:numberToCompareAgainst];

    if (comparisonResult == NSOrderedSame || comparisonResult == NSOrdereedDescending)
        return YES;

    return NO;
}