Objective c “如何修复”；“接收器类型错误”；错误

我正在制作一个应用程序，它允许你设置形状的名称和边数，然后应用程序将自动计算形状名称。我被要求将边数从

NSNumber

更改为

int

。我已经这样做了，但现在我得到一个错误，说“坏接收器类型”。如何更正此问题，但要将边属性的编号保持为int

这是我的类头文件

#import <Foundation/Foundation.h>

@interface shape : NSObject

@property int *numberOfSides;
@property (nonatomic, strong) NSString *name;
@property (nonatomic, strong) NSString *colour;

@property (nonatomic, strong) NSString *calculatedName;

void waitOnCR (void);
- (NSString *)calculatedName;

@end

- (NSString *)calculatedName {
    if ([self.numberOfSides isEqual: @3]) {
        return self.name = @"Triangle";
    }
    else if([self.numberOfSides isEqual: @4]) {
        return self.name = @"Square";
    }
    else if([self.numberOfSides isEqual: @5]) {
        return self.name = @"Pentagon";
    }
    else if([self.numberOfSides isEqual: @6]) {
        return self.name = @"Hexagon";
    }
    else if([self.numberOfSides isEqual: @7]) {
        return self.name = @"Heptagon";
    }
    else if([self.numberOfSides isEqual: @8]) {
        return self.name = @"Octagon";
    }

    return [NSString stringWithFormat:@"%@", self.name ];
}

@end

这是主文件

NSLog(@"Enter a number from between 3-8");

int user;

scanf("%d" , &user);

switch (user) {
    case 3:
    {
        shape *myShape = [[shape alloc]init];
        [myShape setNumberOfSides:3];
        [myShape setColour:@"Red"];
        id s2 = [myShape calculatedName];


        NSLog(@"The %@ shape has %i sides and is called a %@", [myShape colour], [myShape numberOfSides], s2);
        break;
    }
    case 4:
    {
        {
            shape *myShape = [[shape alloc]init];
            [myShape setNumberOfSides:@4];
            [myShape setColour:@"Blue"];
            id s2 = [myShape calculatedName];

            NSLog(@"The %@ shape has %@ sides and is called a %@", [myShape colour], [myShape numberOfSides], s2);
            break;
        }
    case 5:
        {
            shape *myShape = [[shape alloc]init];
            [myShape setNumberOfSides:@5];
            [myShape setColour:@"Orange"];
            id s2 = [myShape calculatedName];

            NSLog(@"The %@ shape has %@ sides and is called a %@", [myShape colour], [myShape numberOfSides], s2);
            break;
        }
    case 6:
        {
            shape *myShape = [[shape alloc]init];
            [myShape setNumberOfSides:@6];
            [myShape setColour:@"Purple"];
            id s2 = [myShape calculatedName];

            NSLog(@"The %@ shape has %@ sides and is called a %@", [myShape colour], [myShape numberOfSides], s2);
            break;
        }
    case 7:
        {
            shape *myShape = [[shape alloc]init];
            [myShape setNumberOfSides:@7];
            [myShape setColour:@"Green"];
            id s2 = [myShape calculatedName];

            NSLog(@"The %@ shape has %@ sides and is called a %@", [myShape colour], [myShape numberOfSides], s2);
            break;
        }
    case 8:
        {
            shape *myShape = [[shape alloc]init];
            [myShape setNumberOfSides:@8];
            [myShape setColour:@"Pink"];
            id s2 = [myShape calculatedName];

            NSLog(@"The %@ shape has %@ sides and is called a %@", [myShape colour], [myShape numberOfSides], s2);
            break;
        }

    }
    default:
        NSLog(@"Shape not found!");
        break;
}

---

numberOfSides

不是一个对象，而是一种基本数据类型，

int

，因此不是：

int *numberOfSides;

你真的想要：

int numberOfSides;

而不是你的

if

语句

if ([self.numberOfSides isEqual: @3]) ...

你想要

if (self.numberOfSides == 3) ...

你的电话是：

[myShape setNumberOfSides:@4];

应该是：

[myShape setNumberOfSides:4];

（你这样做是为了“3”，而不是其他。）

总之，用整数替换所有数字文本（这是一个

NSNumber

对象），并用

=

替换任何

isEqual

，

闻起来像是一个赋值（理论上这很好，但这里的问题很基本。）我投票决定结束>常见问题解答：“询问代码的问题必须表明对正在解决的问题的最低理解。”