如何在Objective-C中将NSString转换为NSMutableString?

Amo*_*ash 12 iphone xcode objective-c ios

有没有办法在Objective-C中将NSString转换为NSMutableString?

Spa*_*yro 25

NSString *string = @"A string.";
NSMutableString *mutableString = [string mutableCopy];
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