Object-C学习代码【第十一章，属性学习】

转载 于 2014-09-10 14:02:00 发布 · 69 阅读 · 0 ·
CC 4.0 BY-SA版权
原文链接：https://my.oschina.net/are1OfBlog/blog/312026
文章标签：

#python

本文详细介绍了如何在Objective-C中进行属性学习与对象创建，包括类与对象的定义、属性的使用、初始化方法和描述方法的实现。通过实例展示了如何创建Car、Tire、Engine等类，并实现了属性的赋值、获取和打印功能。

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//
//  main.m
//  PropertyCar
//
//  Created by on 14-9-9.
//  Copyright (c) 2014年 apple. All rights reserved.
//

//第十一章，属性学习
#import <Foundation/Foundation.h>
#import "Car.h"
#import "Slant6.h"
#import "AllWeatherRadial.h"

int main(int argc, const char * argv[])
{
    @autoreleasepool
    {
        Car *car = [[Car alloc] init];
        car.name = @"Herbie";
        
        for (int i = 0; i < 4; i++)
        {
            AllWeatherRadial *tire;
            
            tire = [[AllWeatherRadial alloc] init];
            tire.rainHandling = 20+i;
            tire.snowHandling = 28+i;
            NSLog(@"tire %d's handling is %.f %.f", i, tire.rainHandling, tire.snowHandling);
            
            [car setTire:tire atIndex:i];
        }
        
        car.engine = [[Slant6 alloc] init];;
        
        [car print];
    }
	return (0);
}

//
//  Tire.h
//  newCar
//
//  Created by on 14-8-19.
//  Copyright (c) 2014年 com.newCar. All rights reserved.
//

@interface Tire : NSObject

@property float pressure;
@property float treadDepth;

- (id) initWithPressure: (float) pressure;
- (id) initWithTreadDepth: (float) treadDepth;

- (id) initWithPressure: (float) pressure
             treadDepth: (float) treadDepth;
@end // Tire

//
//  Tire.m
//  newCar
//
//  Created by on 14-8-19.
//  Copyright (c) 2014年 com.newCar. All rights reserved.
//

#import "Tire.h"

@implementation Tire
@synthesize pressure;
@synthesize treadDepth;

- (id) init
{
    if (self = [self initWithPressure: 34
                           treadDepth: 20]) {
    }
    
    return (self);
    
} // init


- (id) initWithPressure: (float) p
{
    if (self = [self initWithPressure: p
                           treadDepth: 20.0]) {
    }
    
    return (self);
    
} // initWithPressure


- (id) initWithTreadDepth: (float) td
{
    if (self = [self initWithPressure: 34.0
                           treadDepth: td]) {
    }
    
    return (self);
    
} // initWithTreadDepth

- (id) initWithPressure: (float) p
             treadDepth: (float) td
{
    if (self = [super init]) {
        pressure = p;
        treadDepth = td;
    }
    
    return (self);
    
} // initWithPressure:treadDepth:

- (NSString *) description
{
    NSString *desc;
    desc = [NSString stringWithFormat:
            @"Tire: Pressure: %.1f TreadDepth: %.1f",
            pressure, treadDepth];
    return (desc);
    
} // description

@end // Tire

//
//  Engine.h
//  newCar
//
//  Created by on 14-8-19.
//  Copyright (c) 2014年 com.newCar. All rights reserved.
//

#import <Foundation/Foundation.h>

@interface Engine : NSObject

@end

//
//  Engine.m
//  newCar
//
//  Created by on 14-8-19.
//  Copyright (c) 2014年 com.newCar. All rights reserved.
//

#import "Engine.h"

@implementation Engine
- (NSString *)description {
    return (@"I am an engine. Vrooom!");
} // description
@end // Engine

//
//  Slant6.h
//  newCar
//
//  Created by on 14-8-20.
//  Copyright (c) 2014年 com.newCar. All rights reserved.
//

#import "Engine.h"

@interface Slant6 : Engine

@end // Slant6

//
//  Slant6.m
//  newCar
//
//  Created by on 14-8-20.
//  Copyright (c) 2014年 com.newCar. All rights reserved.
//

#import "Slant6.h"

@implementation Slant6
- (NSString *)description {
    return (@"I am a Slant-6, Vrooom!");
} // description
@end // Slant6

//
//  AllWeatherRadial.h
//  newCar
//
//  Created by on 14-8-20.
//  Copyright (c) 2014年 com.newCar. All rights reserved.
//

#import "Tire.h"

@interface AllWeatherRadial : Tire
//如果想让当前类访问实例变量，将实例变量声明在.m的实现文件中，并且删除.h头文件中实例变量的声明
//如果想让从子类直接通过属性来访问变量。这种情况下，变量就必须放在头文件中
//{
//    float rainHandling;
//    float snowHandling;
//}
//@property 是一种新的编译器功能，他意味着声明了一个新对象的属性
//@property预编译指令的作用是自动声明属性的setter和getter方法。
//可以通过-setRainHandling: 来设置属性
//通过调用-rainHanding来访问属性
@property float rainHandling;
@property float snowHandling;
@end // AllWeatherRadial

//
//  AllWeatherRadial.m
//  newCar
//
//  Created by on 14-8-20.
//  Copyright (c) 2014年 com.newCar. All rights reserved.
//

#import "AllWeatherRadial.h"

@implementation AllWeatherRadial
//如果没有指定实例变量，编译器会自动帮我们创建，所以可以清除一下代码
//{
//    float rainHandling;
//    float snowHandling;
//}
//@synthesize也是一种新编译器功能，它表示“创建了该属性的访问代码”。
//当遇到@synthesize rainHandling；这段代码时，编译器将添加实现-setRainHandling: 和 -rainHandling方法的预编译代码
@synthesize rainHandling;
@synthesize snowHandling;

- (id) initWithPressure:(float)p
             treadDepth:(float)td
{
    if (self = [super initWithPressure: p
                            treadDepth: td]) {
        rainHandling = 24.7;
        snowHandling = 42.5;
    }
    
    return (self);
    
} // initWithPressure:treadDepth

- (NSString *) description
{
    NSString *desc;
    desc = [[NSString alloc] initWithFormat:
            @"AllWeatherRadial: %.1f / %.1f / %.1f / %.1f",
//            这里用点来调用方法
//            点表达式是Object-C设计人员有意为之。
//            如果点表达式出现在了等号（=）左边，该变量名称的setter方法将被调用
//            如果点表达式出现在了对象变量的右边，则该变量名称的getter方法将被调用
            self.pressure, self.treadDepth, self.rainHandling, self.snowHandling];
    
    return (desc);
    
} // description

@end // AllWeatherRadial

//
//  Car.h
//  newCar
//
//  Created by on 14-8-19.
//  Copyright (c) 2014年 com.newCar. All rights reserved.
//

@class Tire;
@class Engine;

@interface Car : NSObject

@property (copy) NSString *name;
@property (strong) Engine *engine;

- (void) setTire: (Tire *) tire
         atIndex: (int) index;

- (Tire *) tireAtIndex: (int) index;

- (void) print;

@end // Car

//
//  Car.m
//  newCar
//
//  Created by on 14-8-19.
//  Copyright (c) 2014年 com.newCar. All rights reserved.
//

#import "Car.h"
#import "Engine.h"

@implementation Car
{
    NSMutableArray *tires;
}

@synthesize name = appellation;
@synthesize engine;

- (id) init
{
    if (self = [super init]) {
        self.name = @"Car";
        
        tires = [[NSMutableArray alloc] init];
        
        for (int i = 0; i < 4; i++)
        {
            [tires addObject: [NSNull null]];
        }
    }
    
    return (self);
    
} // init

// dealloc

- (void) setTire: (Tire *) tire
         atIndex: (int) index
{
    [tires replaceObjectAtIndex: index
                     withObject: tire];
    
} // setTire:atIndex:


- (Tire *) tireAtIndex: (int) index
{
    Tire *tire;
    tire = [tires objectAtIndex: index];
    
    return (tire);
    
} // tireAtIndex:


- (void) print
{
    NSLog (@"%@ has:", self.name);
    
    for (int i = 0; i < 4; i++)
    {
        NSLog (@"%@", [self tireAtIndex: i]);
    }
    
    NSLog (@"%@", engine);
    
} // print

@end // Car

//
//  main.m
//  PropertyCar
//
//  Created by on 14-9-9.
//  Copyright (c) 2014年 apple. All rights reserved.
//

//第十一章，属性学习
#import <Foundation/Foundation.h>
#import "Car.h"
#import "Slant6.h"
#import "AllWeatherRadial.h"

int main(int argc, const char * argv[])
{
    @autoreleasepool
    {
        Car *car = [[Car alloc] init];
        car.name = @"Herbie";
        
        for (int i = 0; i < 4; i++)
        {
            AllWeatherRadial *tire;
            
            tire = [[AllWeatherRadial alloc] init];
            tire.rainHandling = 20+i;
            tire.snowHandling = 28+i;
            NSLog(@"tire %d's handling is %.f %.f", i, tire.rainHandling, tire.snowHandling);
            
            [car setTire:tire atIndex:i];
        }
        
        car.engine = [[Slant6 alloc] init];;
        
        [car print];
    }
	return (0);
}



转载于:https://my.oschina.net/are1OfBlog/blog/312026

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