精通ObjectiveC系列 3) 类的申明和实现

如果学过Java和C#的人，这里容易搞混，

Objective-C中的@interface关键字是申明类

@interface Circle : NSObject
{
    @private
    ShapeColor fillColor;
    ShapeRect bounds;
}

- (void) setFillColor: (ShapeColor) fillColor;
- (void) setBounds: (ShapeRect) bounds;
- (void) draw;
@end // Circle

如上，这样的申明类的方式确实让我们Java和C#程序员有点不太习惯，连缩进方式也是

还是来看一下完整代码吧

#import <Foundation/Foundation.h>

// --------------------------------------------------
// constants for the different kinds of shapes and their colors

typedef enum {
    kRedColor,
    kGreenColor,
    kBlueColor
} ShapeColor;


// --------------------------------------------------
// Shape bounding rectangle


typedef struct {
    int x, y, width, height;
} ShapeRect;


// --------------------------------------------------
// convert from the ShapeColor enum value to a human-readable name

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


// --------------------------------------------------
// All about Circles

@interface Circle : NSObject
{
    ShapeColor  fillColor;
    ShapeRect   bounds;
}

- (void) setFillColor: (ShapeColor) fillColor;

- (void) setBounds: (ShapeRect) bounds;

- (void) draw;

@end // Circle


@implementation Circle

- (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




// --------------------------------------------------
// All about Rectangles

@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


// --------------------------------------------------
// All about 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



// --------------------------------------------------
// Draw the shapes

void drawShapes (id shapes[], int count)
{
    for (int i = 0; i < count; i++) {
        id shape = shapes[i];
        [shape draw];
    }
    
} // drawShapes



// --------------------------------------------------
// The main function.  Make the shapes and draw them

int main (int argc, const char * argv[]) 
{
    id shapes[3];
    
    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];
    
    drawShapes (shapes, 3);
    
    return (0);
    
} // main

运行结果：

drawing a circle at (0 0 10 30) in red
drawing a rectangle at (30 40 50 60) in green
drawing an egg at (15 19 37 29) in blue
drawing a triangle at (47 32 80 50) in red