Day13 协议

1 协议，就是class里面必须遵循的约定。例如

@protocol viewControllerDelegate <NSObject>

-(void)loadMoreData;

@end

@interface ViewController ()<viewControllerDelegate>
@property (weak, nonatomic) IBOutlet UITableView *tableView;
@property (nonatomic,strong) NSMutableArray *materialArray;

@end

@implementation ViewController
//必须有loadMoreData
-(void)loadMoreData{}
@end