# NSArray
# Creating NSArray instances
NSArray *array1 = [NSArray arrayWithObjects:@"one", @"two", @"three", nil];
NSArray *array2 = @[@"one", @"two", @"three"];
# Sorting Arrays
The most flexible ways to sort an array is with the sortedArrayUsingComparator: method. This accepts an ^NSComparisonResult(id obj1, id obj2) block.
Return Value Description
NSOrderedAscending obj1 comes before obj2
NSOrderedSame obj1 and obj2 have no order
NSOrderedDescending obj1 comes after obj2
Example:
NSArray *categoryArray = @[@"Apps", @"Music", @"Songs",
@"iTunes", @"Books", @"Videos"];
NSArray *sortedArray = [categoryArray sortedArrayUsingComparator:
^NSComparisonResult(id obj1, id obj2) {
if ([obj1 length] < [obj2 length]) {
return NSOrderedAscending;
} else if ([obj1 length] > [obj2 length]) {
return NSOrderedDescending;
} else {
return NSOrderedSame;
}
}];
NSLog(@"%@", sortedArray);
# Filter NSArray and NSMutableArray
NSMutableArray *array =
[NSMutableArray arrayWithObjects:@"Ken", @"Tim", @"Chris", @"Steve",@"Charlie",@"Melissa", nil];
NSPredicate *bPredicate =
[NSPredicate predicateWithFormat:@"SELF beginswith[c] 'c'"];
NSArray *beginWithB =
[array filteredArrayUsingPredicate:bPredicate];
// beginWith "C" contains { @"Chris", @"Charlie" }.
NSPredicate *sPredicate =
[NSPredicate predicateWithFormat:@"SELF contains[c] 'a'"];
[array filterUsingPredicate:sPredicate];
// array now contains { @"Charlie", @"Melissa" }