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# Classes Bridged to Swift Standard Library Value Types

Use bridged reference types when you need reference semantics or Foundation-specific behavior.

## Topics

### Strings

[`class NSString`](/documentation/Foundation/NSString)

A static, plain-text Unicode string object.

[`class NSMutableString`](/documentation/Foundation/NSMutableString)

A dynamic plain-text Unicode string object.

### Arrays

[`class NSArray`](/documentation/Foundation/NSArray)

A static ordered collection of objects.

[`class NSMutableArray`](/documentation/Foundation/NSMutableArray)

A dynamic ordered collection of objects.

### Dictionaries

[`class NSDictionary`](/documentation/Foundation/NSDictionary)

A static collection of objects associated with unique keys.

[`class NSMutableDictionary`](/documentation/Foundation/NSMutableDictionary)

A dynamic collection of objects associated with unique keys.

### Sets

[`class NSSet`](/documentation/Foundation/NSSet)

A static, unordered collection of unique objects.

[`class NSMutableSet`](/documentation/Foundation/NSMutableSet)

A dynamic unordered collection of unique objects.


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