objective-c new关键字

xxx *a = [xxx new] 等价于 xxx *a = [[xxx alloc]init] ，但如果类的构造函数带参数就不能使用new了。

练习了下《Objective-C 基础教程》第3章代码。

Share.h 头文件

//
//  Share.h
//  SharesDemo01
//
//  Created by apple on 13-7-15.
//  Copyright (c) 2013年 FDStudio. All rights reserved.
//

#import <Foundation/Foundation.h>

typedef enum{
    KCircle,
    KRectangle,
    KOblateSpheroid
} ShareType;

typedef enum{
    KRedColor,
    KGreenColor,
    KBlueColor
} ShareColor;

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

@interface Share : NSObject{
    ShareColor fillColor;
    ShareRect bounds;
}

-(void)setFillColor:(ShareColor)c;
-(void)setBounds:(ShareRect)rect;
-(NSString *) ColorName:(ShareColor) c;
-(void)draw;

@end    //Share

@interface Circle : Share

@end    //Circle

@interface Rectangle : Share

@end    //Rectangle

Share.m 实现文件

//
//  Share.m
//  SharesDemo01
//
//  Created by apple on 13-7-15.
//  Copyright (c) 2013年 FDStudio. All rights reserved.
//

#import "Share.h"

@implementation Share

-(void)setFillColor:(ShareColor)c{
    fillColor = c;
}   //setFillColor

-(void)setBounds:(ShareRect)rect{
    bounds = rect;
}   //setBounds

-(NSString *)ColorName:(ShareColor)c{
    switch (c) {
        case KRedColor:
            return @"red";
            break;
        case KBlueColor:
            return @"blue";
            break;
        case KGreenColor:
            return @"green";
            break;
    }
    return @"no clue";
}

-(void)draw{

}   //draw
@end    //Share

@implementation Circle

-(void)draw{
    NSLog(@"drawing a circle at (%d %d %d %d) in %@", bounds.x, bounds.y,bounds.width,bounds.height, [self ColorName:fillColor]);
}

@end    //Circel

@implementation Rectangle

-(void)draw{
    NSLog(@"drawing a Rectangle at (%d %d %d %d) in %@", bounds.x, bounds.y,bounds.width,bounds.height, [self ColorName:fillColor]);
}

@end

main.m 主文件

//
//  main.m
//  SharesDemo01
//
//  Created by apple on 13-7-15.
//  Copyright (c) 2013年 FDStudio. All rights reserved.
//

#import <Foundation/Foundation.h>
#import "share.h"

int main(int argc, const char * argv[])
{

    @autoreleasepool {

        // insert code here...
        id shares[2];

        ShareRect rect0 = {0,0,10,30};
        shares[0] = [Circle new];
        [shares[0] setBounds:rect0];
        [shares[0] setFillColor:KRedColor];

        ShareRect rect1 = {30,40,50,60};
        shares[1] = [Rectangle new];
        [shares[1] setBounds:rect1];
        [shares[1] setFillColor:KBlueColor];

        for(int i=0; i<2; i++){
            [shares[i] draw];
        }
    }
    return 0;
}