November 2013
Beginner
325 pages
9h 47m
English
Content preview from Objective-C Programming: The Big Nerd Ranch Guide
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Filtering
When you filter a collection, you compare its objects to a logical statement to get a resultant collection that only contains objects for which the statement is true.
A predicate contains a statement that might be true, like “The employeeID is greater than 75.” There is a class called NSPredicate. NSMutableArray has a handy method for discarding all the objects that do not satisfy the predicate:
- (void)filterUsingPredicate:(NSPredicate *)predicate;
With NSArray, you cannot remove objects that do not match the predicate. Instead, NSArray has a method that creates a new array that contains all the objects that satisfy the predicate:
- (NSArray *)filteredArrayUsingPredicate:(NSPredicate *)predicate;
Imagine that ...
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