一、声明类接口步骤：
1、声明一个类接口，使用@interface关键字加上类名称。
2、用 { 实例变量 } 来定义各种数据成员。
3、方法声明，采用中缀符语法声明一个c函数，用到了冒号 ： 。
二、声明类接口实例：
//声明圆形circle类接口
@interface Circle : NSObject
{
ShapeColor fillColor;//每次创建新的Circle对象后，对象中都包括这两个元素——类的实例变量
ShapeRect bounds;
}//指定实例变量
-(void) setFillColor: (ShapeColor) fillColor;//方法声明、中缀符
-(void) setBounds: (ShapeRect) bounds;
-(void) draw;
@end //Circle 完成类的声明
三、实现类步骤
1、用关键字@implementation加上类名称
2、实现类中声明的方法，编写方法体 { 方法体 } 。
四、实现类实例
@implementation Circle//类实现
-(void) setFillColor: (ShapeColor) c
{
fillColor = c;
}//setFillColor
-(void) setBounds: (ShapeRect) b
{
bounds = b;
}//setbounds
-(void) draw
{
NSLog(@"drawing a circle at(%d %d %d %d) in %@",
bounds.x,bounds.y,bounds.width,bounds.height,colorName(fillColor)
);
}//draw
@end//Circle 完成类的实现
五、案例练习——几何图形的绘制和填充颜色
//
// main.m
// Shapes-Object
//
// Created by jason on 14-6-10.
// Copyright (c) 2014年 JasonApp. All rights reserved.
//
#import <Foundation/Foundation.h>
//定义形状的不同颜色
typedef enum{
kRedColor,
kGreenColor,
kBlueColor
} ShapeColor;
//定义一个矩形来指定屏幕上的绘制区域
typedef struct{
int x,y,width,height;
} ShapeRect;
//负责转换传入的颜色值，并返回NSString字面量
NSString *colorName(ShapeColor color)
{
switch (color) {
case kRedColor:
return @"Red";
break;
case kGreenColor:
return @"Green";
break;
case kBlueColor:
return @"Blue";
break;
}
return @"no clue";
}//colorName
//声明圆形circle类接口
@interface Circle : NSObject
{
ShapeColor fillColor;//每次创建新的Circle对象后，对象中都包括这两个元素——类的实例变量
ShapeRect bounds;
}//指定实例变量
-(void) setFillColor: (ShapeColor) fillColor;//方法声明、中缀符
-(void) setBounds: (ShapeRect) bounds;
-(void) draw;
@end //Circle 完成类的声明
@implementation Circle//类实现
-(void) setFillColor: (ShapeColor) c
{
fillColor = c;
}//setFillColor
-(void) setBounds: (ShapeRect) b
{
bounds = b;
}//setbounds
-(void) draw
{
NSLog(@"drawing a circle at(%d %d %d %d) in %@",
bounds.x,bounds.y,bounds.width,bounds.height,colorName(fillColor)
);
}//draw
@end//Circle 完成类的实现
//定义矩形
@interface Rectangle : NSObject
{
ShapeColor fillColor;
ShapeRect bounds;
}
- (void) setFillColor: (ShapeColor) fillColor;
- (void) setBounds: (ShapeRect) bounds;
- (void) draw;
@end // Rectangle
@implementation Rectangle
- (void) setFillColor: (ShapeColor) c
{
fillColor = c;
} // setFillColor
- (void) setBounds: (ShapeRect) b
{
bounds = b;
} // setBounds
- (void) draw
{
NSLog (@"drawing a rectangle at (%d %d %d %d) in %@",
bounds.x, bounds.y,
bounds.width, bounds.height,
colorName(fillColor));
} // draw
@end // Rectangle
//定义OblateSphereoids
@interface OblateSphereoid : NSObject
{
ShapeColor fillColor;
ShapeRect bounds;
}
- (void) setFillColor: (ShapeColor) fillColor;
- (void) setBounds: (ShapeRect) bounds;
- (void) draw;
@end // OblateSphereoid
@implementation OblateSphereoid
- (void) setFillColor: (ShapeColor) c
{
fillColor = c;
} // setFillColor
- (void) setBounds: (ShapeRect) b
{
bounds = b;
} // setBounds
- (void) draw
{
NSLog (@"drawing an egg at (%d %d %d %d) in %@",
bounds.x, bounds.y,
bounds.width, bounds.height,
colorName(fillColor));
} // draw
@end // OblateSphereoid
//定义三角形
@interface Triangle : NSObject
{
ShapeColor fillColor;
ShapeRect bounds;
}
- (void) setFillColor: (ShapeColor) fillColor;
- (void) setBounds: (ShapeRect) bounds;
- (void) draw;
@end // Triangle
@implementation Triangle
- (void) setFillColor: (ShapeColor) c
{
fillColor = c;
} // setFillColor
- (void) setBounds: (ShapeRect) b
{
bounds = b;
} // setBounds
- (void) draw
{
NSLog (@"drawing a triangle at (%d %d %d %d) in %@",
bounds.x, bounds.y,
bounds.width, bounds.height,
colorName(fillColor));
} // draw
@end // Triangle
//画形状
void drawShapes (id shapes[], int count)
{
for (int i = 0; i < count; i++) {
id shape = shapes[i];
[shape draw];
}
}//drawShapes
int main(int argc, const char * argv[])
{
id shapes[4];
ShapeRect rect0 = { 0, 0, 10, 30 };
shapes[0] = [Circle new];
[shapes[0] setBounds: rect0];
[shapes[0] setFillColor: kRedColor];
ShapeRect rect1 = { 30, 40, 50, 60 };
shapes[1] = [Rectangle new];
[shapes[1] setBounds: rect1];
[shapes[1] setFillColor: kGreenColor];
ShapeRect rect2 = { 15, 19, 37, 29 };
shapes[2] = [OblateSphereoid new];
[shapes[2] setBounds: rect2];
[shapes[2] setFillColor: kBlueColor];
ShapeRect rect3 = { 47, 32, 80, 50 };
shapes[3] = [Triangle new];
[shapes[3] setBounds: rect3];
[shapes[3] setFillColor: kRedColor];
drawShapes (shapes, 4);
return (0);
}
六、小结
1、过程式编程——“函数第一，数据第二”
2、OOP——“数据第一，函数第二”
3、“开放/关闭原则”——软件实体应该对拓展开放、对修改关闭
4、objective-c中不存在private方法
5、objective-c运行时负责执行重要的任务，比如对象发送消息和传递参数等，以支持应用程序的运行
6、实例化对象——向相应的类发送new消息来创建对象。
