在Objective-C中是否有(stringByAppendingString:)字符串连接的快捷方式，或者通常使用NSString的快捷方式？
例如，我想:
NSString *myString = @"This";
NSString *test = [myString stringByAppendingString:@" is just a test"];
更像是:
string myString = "This";
string test = myString + " is just a test";