NSString *string = @"How are you";
NSLog(@"uppercaseString:%@", string.uppercaseString); //全部大写
NSLog(@"lowercaseString:%@", string.lowercaseString); //全部小写
NSLog(@"capitalizedString:%@", string.capitalizedString); //首字母大写
打印数据:
uppercaseString:HOW ARE YOU
lowercaseString:how are you
capitalizedString:How Are You