菜鸟问一个objective-c的初级问题

[luhon]

#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



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

@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


// --------------------------------------------------
// 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[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);

} // main
同样的代码，教材实例，我拷贝的就报错，教材源码就可以运行，为什么?

[泉哥爱phone干货]

你截图的这个项目创建的时候应该是选的ARC ，而代码是MRC ，建议修改配置后再看看

[scribbler]

改成这样试试

// 定义
__unsafe_unretained id shapes[4];

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