学习笔记(objective-c)-扩展(extension)

最新推荐文章于 2019-07-23 15:19:33 发布

转载最新推荐文章于 2019-07-23 15:19:33 发布 · 388 阅读

ios 专栏收录该内容

8 篇文章

订阅专栏

本文介绍Objective-C中如何使用类扩展来增加现有类的功能，并通过一个具体的APPLECar类的例子展示了如何添加新的实例变量和方法。

定义扩展的语法如下：

@interface class ()

@end

扩展用于临时对已有类的接口进行扩展。扩展与类别的不同是可以额外追加实例变量。

例：

#import <Foundation/Foundation.h>

@interface APPLECar : NSObject
@property (nonatomic,copy) NSString* brand;
@property (nonatomic,copy) NSString* model;
-(void) drive;
@end

//对APPLECar扩展
#import "APPLECar.h"

@interface APPLECar ()
@property (nonatomic,copy) NSString* color;
-(void)drive:(NSString*)owner;
@end

//类实现部分

#import "APPLECar+drive.h"

@implementation APPLECar
@synthesize brand;
@synthesize model;
@synthesize color;
-(void)drive
{
NSLog(@"%@ are on the road running",self);
}
-(void)drive:(NSString*)owner
{
NSLog(@"%@ driving the %@ car on the road",owner,self);
}
-(NSString*)description
{
return [NSString stringWithFormat:@"brand=%@,model=%@,color=%@",self.brand,self.model,self.color];
}
@end

#import "APPLECar+drive.h"

int main(int argc,char* argv[])
{
@autoreleasepool{
APPLECar* car = [[APPLECar alloc]init];
car.brand = @"BMW";
car.model = @"X5";
car.color = @"red";
[car drive];
[car drive:@"tom"];
}
}