objective-C 的OOP(上)--类定义、继承及方法调用
如何改用OOP的方法来实现：
因为要用到“颜色”以及“矩形区域”二个枚举，先把他们抽出来单独放在CommDef.h文件中
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//定义“几何形状颜色”枚举 |
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typedef enum |
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{ |
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kRedColor, |
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kGreenColor, |
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kBlueColor |
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} ShapeColor; |
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//定义“几何形状矩形区域”结构 |
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typedef struct |
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{ |
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int x,y,width,height; |
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} ShapeRect; |
然后再定义基类Shape，注意：在obj-C中，定义一个类通常分成二部分，一部分是".h"的文件，用来申明类有哪些成员（也称为类的定义文件，类似于接口），另一部分是".m"的文件，用来提供具体实现
Shape类的申明部分如下:(Shape.h)
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// |
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// Shape.h |
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// HelloWorld |
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// |
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// Created by jimmy.yang on 11-1-26. |
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// Copyright 2011 __MyCompanyName__. All rights reserved. |
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// |
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#import "CommDef.h" |
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@interface Shape : NSObject { |
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ShapeColor fillColor; |
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ShapeRect bounds; |
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} |
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- (void) setFillColor:(ShapeColor) fillColor; |
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- (void) setBounds:(ShapeRect) bounds; |
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- (void) draw; |
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- (NSString*) getColorName:(ShapeColor) fillColor; |
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@end //Shape |
Shape类的实现部分如下:(Shape.m)
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// |
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// Shape.m |
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// HelloWorld |
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// |
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// Created by jimmy.yang on 11-1-26. |
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// Copyright 2011 __MyCompanyName__. All rights reserved. |
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// |
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#import "Shape.h" |
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@implementation Shape |
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- (void) setBounds:(ShapeRect)b |
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{ |
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bounds = b; |
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} |
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- (void) setFillColor:(ShapeColor)f |
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{ |
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fillColor =f; |
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} |
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//注：这个方法留给子类去实现，所以这里只要一个空壳就行了 |
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- (void) draw |
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{ |
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|
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} |
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- (NSString*) getColorName:(ShapeColor)f |
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{ |
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|
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switch (f) { |
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case kRedColor: |
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return @"red"; |
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break; |
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case kGreenColor: |
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return @"green"; |
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break; |
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case kBlueColor: |
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return @"blue"; |
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break; |
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default: |
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return @"no clue"; |
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break; |
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} |
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|
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} |
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@end |
语法有点奇怪，初次接触，只能强迫自己忘记吧。
然后定义子类Circle
申明部分Circle.h
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// |
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// Circle.h |
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// HelloWorld |
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// |
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// Created by jimmy.yang on 11-1-26. |
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// Copyright 2011 __MyCompanyName__. All rights reserved. |
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// |
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#import "Shape.h" |
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//注：因为Circle类不需要扩展其它方法，所以这里也只要一个空壳 |
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@interface Circle : Shape { |
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} |
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@end |
实现部分Circle.m
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// |
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// Circle.m |
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// HelloWorld |
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// |
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// Created by jimmy.yang on 11-1-26. |
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// Copyright 2011 __MyCompanyName__. All rights reserved. |
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// |
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#import "Circle.h" |
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@implementation Circle |
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-(void) draw |
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{ |
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NSLog(@"drawing a Cirle at (%d,%d,%d,%d) in %@",bounds.x,bounds.y,bounds.width,bounds.height,[super getColorName:fillColor]); |
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} |
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@end |
注：上面展示了在obj-C中如何调用父类的方法[super getColorName:fillColor]
子类Rectangle
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// |
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// Rectangle.h |
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// HelloWorld |
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// |
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// Created by jimmy.yang on 11-1-26. |
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// Copyright 2011 __MyCompanyName__. All rights reserved. |
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// |
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#import "Shape.h" |
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@interface Rectangle : Shape { |
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} |
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@end |
实现部分
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// |
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// Rectangle.m |
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// HelloWorld |
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// |
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// Created by jimmy.yang on 11-1-26. |
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// Copyright 2011 __MyCompanyName__. All rights reserved. |
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// |
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#import "Rectangle.h" |
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@implementation Rectangle |
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-(void) draw |
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{ |
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NSLog(@"drawing a Rectangle at (%d,%d,%d,%d) in %@",bounds.x,bounds.y,bounds.width,bounds.height,[super getColorName:fillColor]); |
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} |
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@end |
子类Ellipse
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// |
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// Ellipse.h |
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// HelloWorld |
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// |
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// Created by jimmy.yang on 11-1-26. |
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// Copyright 2011 __MyCompanyName__. All rights reserved. |
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// |
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#import "Shape.h" |
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@interface Ellipse : Shape{ |
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} |
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@end |
实现部分
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// |
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// Ellipse.m |
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// HelloWorld |
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// |
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// Created by jimmy.yang on 11-1-26. |
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// Copyright 2011 __MyCompanyName__. All rights reserved. |
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// |
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#import "Ellipse.h" |
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@implementation Ellipse |
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-(void) draw |
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{ |
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NSLog(@"drawing a ellipse at (%d,%d,%d,%d) in %@",bounds.x,bounds.y,bounds.width,bounds.height,[super getColorName:fillColor]); |
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} |
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@end |
最后看下调用的主函数HelloWorld.m
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#import "CommDef.h" |
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#import "Circle.h" |
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#import "Rectangle.h" |
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#import "Ellipse.h" |
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int main (int argc, const char * argv[]) { |
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|
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id shape[2] ; |
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|
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ShapeRect rect0 = {0,0,10,30}; |
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shape[0] = [Circle new]; |
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[shape[0] setBounds:rect0]; |
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[shape[0] setFillColor:kGreenColor]; |
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[shape[0] draw]; |
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|
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ShapeRect rect1 = {0,0,40,50}; |
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shape[1] = [Rectangle new]; |
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[shape[1] setBounds:rect1]; |
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[shape[1] setFillColor:kRedColor]; |
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[shape[1] draw]; |
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|
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ShapeRect rect2 = {0,0,30,30}; |
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shape[2] = [Ellipse new]; |
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[shape[2] setBounds:rect2]; |
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[shape[2] setFillColor:kBlueColor]; |
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[shape[2] draw]; |
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|
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return 0; |
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} |
注：上面的代码中有一个id的变量，在obj-C中id相当于“任意类型”，意为指向某对象的指针（哪怕你不知道这个对象是什么类型），总之，如果你不知道某对象的具体类型时，用它就对了。同时我们也看到了，创建一个类的实例用“[类 new]”来完成。
最后附上文件结构图:
