How might I check if a particular NSString is present in an NSArray?

问题

How might I check if a particular NSString is presnet in an NSArray?

回答1:

You can do it like,

NSArray* yourArray = [NSArray arrayWithObjects: @"Str1", @"Str2", @"Str3", nil];
if ( [yourArray containsObject: yourStringToFind] ) {
    // do found
} else {
    // do not found
}

回答2:

Iterating or containsObject are order n ways to find.

If you want constant time lookup, you can also maintain a hash table like NSSet or NSHashTable but that increases space but saves time.

NSArray* strings = [NSArray arrayWithObjects: @"one", @"two", @"three", nil];
NSSet *set = [NSSet setWithArray:strings];

NSString* stringToFind = @"two";
NSLog(@"array contains: %d", (int)[strings containsObject:stringToFind]);
NSLog(@"set contains: %d", (int)[set containsObject:stringToFind]);

回答3:

Depends on your needs. Either indexOfObject if you care about equality (most likely), or indexOfObjectIdenticalTo if you care it's actually the same object (i.e. same address).

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