代理模式

int main(int argc, const char * argv[])
{

    Person *person = [[Person alloc]init];
    
    Ticker *ticker = [[Ticker alloc]init];
    
    person.delegate=ticker;
    
    [person buyTicker];

    return 0;
}

Person.h
@interface Person : NSObject

@property (nonatomic, strong) id<TickerDelegate> delegate;

-(void)buyTicker;

@end

Person.m
@implementation Person
-(void)buyTicker
{
    int num = [_delegate getTickerNumber];
    double price = [_delegate getTickePrcie];
    NSLog(@"%d, %f", num, price);
}
@end

Ticker.h
@interface Ticker : NSObject<TickerDelegate>
@end

Ticker.m
@implementation Ticker
-(double)getTickePrcie
{
    return 50;
}

-(int)getTickerNumber
{
    return 10;
}
@end

TickerDelegate.h
@protocol TickerDelegate <NSObject>
-(int)getTickerNumber;
-(double)getTickePrcie;
@end