objective-c - Objective－c的复合疑问

Question

1.这个例子是objective－c程序设计 11章的合成对象的练习
2.程序没有报错，但提示有个实例变量没有使用
3.mian（）程序中打印的数字不正确，不知道哪里出了问题！！
代码：
Rectangle

#import <Foundation/Foundation.h>

@interface Rectangle : NSObject

@property int width,height;

-(instancetype) initWithWidth:(int) w Height:(int) h;
-(int) area;
-(int) primeter;
@end

#import "Rectangle.h"

@implementation Rectangle

@synthesize width,height;

-(instancetype) initWithWidth:(int)w Height:(int)h{
    
    if (self = [super init]) {
        width = w;
        height= h;
    }
    
    return self;
}

-(int) area{
    return width*height;
}

-(int) primeter{
    return (width+height)*2;
}

@end


Square
#import <Foundation/Foundation.h>
#import "Rectangle.h"

@interface Square : NSObject
{
    Rectangle *rect;
}

@property int Side;

-(instancetype) initWithSide:(int) s;
-(void) setSide:(int) s;
-(int) Side;
-(int) area;
-(int) perimeter;


@end

#import "Square.h"


@implementation Square

@synthesize Side;

-(instancetype) init{
    
    if (self = [super init]) {
        self = [[Square alloc] initWithSide:0];
    }
    
    return self ;
}

-(instancetype) initWithSide:(int)s{
    if (self = [super init]){
//        Rectangle *rect = [[Rectangle alloc] initWithWidth:s Height:s];
    [rect initWithWidth:s Height:s];
    }
    
    return  self;
}

-(void) setSide:(int)s{
    Side = s;
}

-(int) Side{
    return  Side;
}

-(int) area{
    return [rect area];
}

-(int) perimeter{
    return [rect primeter];
}
@end


main()函数


#import <Foundation/Foundation.h>
#import "Square.h"
#import "Rectangle.h"

int main(int argc, const char * argv[]) {
    @autoreleasepool {
        
        Square *sq = [[Square alloc] initWithSide:50];
        
        NSLog(@"正方形的边长%i",[sq area]);
        NSLog(@"正方形的面积%i",[sq perimeter]);

    }
    return 0;
}

Answer 1

rect is not a member variable, and you checked out Rectangle *rect = [[Rectangle alloc] initWithWidth:s Height:s]; Of course, [sq area] and [sq perimeter] cannot be typed