1 #define NS_DESIGNATED_INITIALIZER __attribute__((objc_designated_initializer)) 2 3 @class NSString; 4 5 @interface B1 6 -(instancetype)init; 7 @end 8 9 @interface S1 : B1 10 @property (nonatomic) int prop; 11 +(instancetype)s1; 12 -(instancetype)initWithFoo:(NSString*)foo NS_DESIGNATED_INITIALIZER; 13 @end 14