protocol类似@class方式使用, 能提高效率, 但是有警告.

main.m

#import "Dog.h"#import "baseProtocol.h"#import <Foundation/Foundation.h>int main(int argc, const char * argv[]){@autoreleasepool {Dog * dog = [[Dog alloc] init];[dog run];}return 0;}

baseProtocol.h

#import <Foundation/Foundation.h>@protocol baseProtocol <NSObject>- (void)run;@end

Dog.h

#import <Foundation/Foundation.h>@protocol baseProtocol;@interface Dog : NSObject <baseProtocol> // 提示警告 :Cannot find protocol definition for 'baseProtocol' // 可以运行,但是有警告xcode7.0 不爽@end

Dog.m

#import "Dog.h"#import "baseProtocol.h"@implementation Dog- (void)run{NSLog(@"dog is running");}@end