IOS/Objective-C: Class接口错误中的方法

Question

我从一个没有导致错误的教程中复制了以下内容到我的项目中，它在指示的行上导致了三个错误。（错误似乎不正确，因为当我尝试修复它们时，会出现其他错误。）任何人都可以提出可能是什么问题：

@interface VC ()
   NSDictionary(JSONCategories) //MULTIPLE ERRORS THIS LINE including cannot declare variables inside @interface
+(NSDictionary*)dictionaryWithContentsOfJSONURLString:(NSString*)urlAddress;
-(NSData*)toJSON;
@end

Answer 1

这是一个 NSDictionary 类别；你想要：

@interface NSDictionary(JSONCategories)
+(NSDictionary*)dictionaryWithContentsOfJSONURLString:(NSString*)urlAddress;
-(NSData*)toJSON;
@end

Apple Reference.

Answer 2

我假设您正在尝试创建一个类别：

a category interface looks exactly like a normal interface, except the class name is followed by the category name in parentheses.

例如类别应声明为：

#import "Car.h"

@interface Car (Maintenance)   //Maintainence is a category

- (BOOL)needsOilChange;
- (void)changeOil;
- (void)rotateTires;
- (void)jumpBatteryUsingCar:(Car *)anotherCar;

@end

IOS/Objective-C: Class接口错误中的方法

IOS/Objective-C: Class Method in Interface Error

objective-c

class-method

ios