以相反的顺序对 NSArray 进行排序

Question

NSArray* sortedArray = [myArray sortedArrayUsingSelector:@selector(compare:)];

Just wondering how I can sort this array of numbers in descending order?

Answer 1

Either use the method that allows you to pass a block as a comparator and implement a comparator that reverses the objects (returns NSOrderedAscending for NSOrderedDescending and vice versa)....

... or:

NSArray *reversed = [[[myArray sortedArrayUsingSelector:@selector(compare:)] reverseObjectEnumerator] allObjects];

Sorry. Derped the most important part.

Answer 2

Use NSSortDescriptor

NSSortDescriptor* sortOrder = [NSSortDescriptor sortDescriptorWithKey: @"self" ascending: NO];
NSArray *temp = [myArray sortedArrayUsingDescriptors: [NSArray arrayWithObject: sortOrder]];

Answer 3

I like to use the sortedArrayUsingFunction: method which gives full control of how the array is sorted. Then to reverse the results return the negative value of what you would have returned.

NSInteger myCompare (id obj1, id obj2, void *context) {
    int retval = [obj1 compare:obj2 options:NSNumericSearch];
    retval = -retval; // now it's sorted reverse
    return retval;
}

...

NSArray *arr = @[@"foo20zz", @"foo7zz", @"foo100zz"];
NSArray *sarr = [arr sortedArrayUsingFunction:myCompare context:NULL];
NSLog(@"sarr is %@", sarr);