本來分類和協議應該是放在同一篇來寫的,可是最近有點小感冒,這兩天不在狀態,於是現在補上。
協議(protocol)
1.在我看來,目前而言,IOS的協議其實是與Android的接口是同一個概念,包括作用與實現。其作用很好的規範了對象們屬性的統一性。
2.前段時間在一個線下活動中聽說swift主張面向協議編程,當時百思不得其解,後來才明白其實也就等同於面向接口編程。其實與面向對象的思想並不相悖。
3.protocol中有個可選屬性optional的概念,在這裏不太明白:對等java中似乎沒有這個屬性,在此也思考是否有存在這個屬性的必要,如果這個方法是可選的,爲什麼不將它寫在父類中,而要寫在協議裏,這樣豈不是有悖於其統一性的初衷了嗎?
寫了個小demo,代碼如下:
基類
#import <Foundation/Foundation.h>
@interface animals : NSObject
-(BOOL) isBelongAnimals;
@end
#import "animals.h"
@implementation animals
-(BOOL)isBelongAnimals
{
return true;
}
@end
protocol
#import <Foundation/Foundation.h>
#import "animals.h"
@protocol animalHabits
-(void) eat;
-(void) sleep;
@optional
-(BOOL)isLazy;
@end
#import "animalHabits.h"
@implementation animalHabits : NSObject
@end
Panda
#import <Foundation/Foundation.h>
#import "animals.h"
#import "animalHabits.h"
@interface Panda : animals <animalHabits>
@end
#import "Panda.h"
@implementation Panda
//因爲實現了animalHabits這個協議(接口),所以sleep 和 eat方法必須實現,否則會報錯
//接口在此作爲一個方法統一的作用,因爲每一個動物都需要去吃飯和睡覺
-(void)sleep
{
NSLog(@"Panda always sleeping 14 hours every day!");
}
-(void)eat
{
NSLog(@"Panda favorite food is bamboo!");
}
-(BOOL)isLazy
{
NSLog(@"Panda is very lazy!");
return true;
}
@end
Dog
#import <Foundation/Foundation.h>
#import "animalHabits.h"
#import "animals.h"
@interface Dog : animals<animalHabits>
-(void)skill;
@end
#import "Dog.h"
@implementation Dog
-(void)sleep
{
NSLog(@"dog always sleep for 6 hours a day");
}
-(void)eat
{
NSLog(@"dog like bone!");
}
-(void)skill
{
NSLog(@"dog can protect our house!");
}
@end
main.m
#import <Foundation/Foundation.h>
#import "Panda.h"
#import "Dog.h"
int main(int argc, const char * argv[])
{
@autoreleasepool {
Panda *panda = [[Panda alloc] init];
if ([panda isBelongAnimals]){
[panda sleep];
[panda eat];
}
Dog *dog = [[Dog alloc] init];
[dog skill];
}
return 0;
}
輸出結果:
2015-09-17 20:43:53.300 Lesson4[610:303] Panda always sleeping 14 hours every day!
2015-09-17 20:43:53.302 Lesson4[610:303] Panda favorite food is bamboo!
2015-09-17 20:43:53.303 Lesson4[610:303] dog can protect our house!
Program ended with exit code: 0