cocoa - 我非常感谢新 Cocoa 程序员的帮助

Question

我正在为设计游戏的女儿制作一个简单的程序。我只是想让 Mac 给出一个从 1 到 6 的随机数，将其与用户的猜测进行比较，然后得到差值，该差值用于确定玩家可以在棋盘游戏中移动多少个空格。一切正常，除了程序生成的差值始终为 3。它正确生成随机数并正确读取用户的输入。这是代码。我真的很感激帮助。我对此很陌生，并且意识到可能有一个非常非常简单的答案。我一直在寻找，并没有找到解决方案。在某一时刻它可以正确地产生差异，但现在却不能了。非常感谢!

//
//  AstroGuessAppDelegate.h
//
//  Created by Trent Evans on 3/7/11.
//  Copyright 2011 __MyCompanyName__. All rights reserved.
//

#import <Cocoa/Cocoa.h>

int macPick;
int numberGuess;
int numberDiff;

@interface AstroGuessAppDelegate : NSObject {
    IBOutlet NSWindow *window;
    IBOutlet id moveResultLabel;
    IBOutlet id thinkingLabel;
    IBOutlet NSComboBox *numberGuessBox;
}
- (IBAction)compareNumbersAndSendResults:(id)sender;
- (IBAction)macThinkOfNumber:(id)sender;
@end



//
//  AstroGuessAppDelegate.m
//
//  Created by Trent Evans on 3/7/11.
//  Copyright 2011 __MyCompanyName__. All rights reserved.
//

#import "AstroGuessAppDelegate.h"

@implementation AstroGuessAppDelegate


- (IBAction)macThinkOfNumber:(id)sender {

    macPick = (arc4random() % 6) + 1;
    NSString *thinkingLabelText = [NSString stringWithFormat: @"Ok. I'm thinking of a number."];
    [thinkingLabel setStringValue:thinkingLabelText];

}

- (IBAction)compareNumbersAndSendResults:(id)sender {

    numberGuess = [numberGuessBox intValue];
    numberDiff = macPick - numberGuess;
    if (numberDiff<0) {
        numberDiff = numberDiff * -1;
    }
    NSString *moveResultLabelText;
    if (numberDiff=0) {
        moveResultLabelText = [NSString stringWithFormat:@"My number was %i. Your number was %i. The difference is %i. \nBLAST OFF!\nMove forward 6 spaces", macPick, numberGuess, numberDiff];
    }
    if (numberDiff=1) {
        moveResultLabelText = [NSString stringWithFormat:@"My number was %i. Your number was %i. The difference is %i. \nORBIT!\nMove forward 4 spaces", macPick, numberGuess, numberDiff];

    }
    if (numberDiff=2) {
        moveResultLabelText = [NSString stringWithFormat:@"My number was %i. Your number was %i. The difference is %i. \nRE-ENTRY!\nMove forward 2 spaces", macPick, numberGuess, numberDiff];

    }
    if (numberDiff=3) {
        moveResultLabelText = [NSString stringWithFormat:@"My number was %i. Your number was %i. The difference is %i. \nSPLASHDOWN!\nMove forward 1 space", macPick, numberGuess, numberDiff];

    }
    else {
        moveResultLabelText = [NSString stringWithFormat:@"My number was %i. Your number was %i. The difference is %i. \nBLACK HOLE!\nSorry. You don't get to move.", macPick, numberGuess, numberDiff];

    }


    [moveResultLabel setStringValue:moveResultLabelText];

}


@end

Answer 1

在您的 if 语句中，您使用的是赋值运算符 = 而不是比较运算符 ==，因此每个 if 为 true，最后执行的是 3。

为此，您最好使用switch:

switch(numberDiff)
{  case 0:
       moveResultLabelText = [NSString stringWithFormat:@"My number was %i. Your number was %i. The difference is %i. \nBLAST OFF!\nMove forward 6 spaces", macPick, numberGuess, numberDiff];
       break;
   case 1:
      etc.
   default:
      moveResultLabelText = [NSString stringWithFormat:@"My number was %i. Your number was %i. The difference is %i. \nBLACK HOLE!\nSorry. You don't get to move.", macPick, numberGuess, numberDiff];
}

接下来，您已将所有变量声明为顶部的文件全局变量:

int macPick;
int numberGuess;
int numberDiff;

如果这些在不同方法之间共享，那么它们应该是实例变量，在这种情况下，macPick 是一个实例变量。这应该在@interface中声明:

@interface AstroGuessAppDelegate : NSObject
{
   int macPick;
   etc.

看起来其他两个仅由 compareNumbersAndSendResults 使用，因此在那里声明它们:

- (IBAction)compareNumbersAndSendResults:(id)sender
{
   int numberGuess;
   int numberDiff;
   etc.

有一个小的注释更改:

numberDiff = numberDiff * -1;

至

numberDiff = -numberDiff;

甚至使用abs函数:

numberDiff = abs(macPick - numberGuess);