NSMutable object initialized with initial storage for a given number of characters,
- iOS 2.0+
- macOS 10.0+
- tvOS 9.0+
- watchOS 2.0+
The number of characters the string is expected to initially contain.
NSMutable object with initial storage for
capacity characters. The returned object might be different than the original receiver.
The number of characters indicated by
capacity is simply a hint to increase the efficiency of data storage. The value does not limit the length of the string.