Question

So, I have a class called MazeCell which is declared in “MazeCell.h”

#import <Foundation/Foundation.h>

enum {
    MazeCellEdgeWall = 0,
    MazeCellEdgeGate = 1,
    MazeCellEdgeExit = 2
};
typedef NSUInteger MazeCellEdge;

@interface MazeCell : NSObject {
    MazeCellEdge left;
    MazeCellEdge right;
    MazeCellEdge down;
    MazeCellEdge up;
    NSUInteger drawCount;
    NSUInteger row;
    NSUInteger column;
}
@property MazeCellEdge left;
@property MazeCellEdge right;
@property MazeCellEdge down;
@property MazeCellEdge up;
@property NSUInteger drawCount;
@property NSUInteger row;
@property NSUInteger column;

- (id)initWithLeft:(MazeCellEdge)newLeft
             right:(MazeCellEdge)newRight
                up:(MazeCellEdge)newUp
              down:(MazeCellEdge)newDown
               row:(NSUInteger)newRow
            column:(NSUInteger)newColumn;
@end

Xcode keeps displaying warnings like "warning: 'MazeView' may not respond to '-left'" for all the methods. The funny thing is that the code runs fine on the simulator, it’s just that XCode doesn’t know the methods.

I was content to ignore the messages until XCode wouldn’t let me use MazeCellEdgeWall because it hadn’t been declared earlier (all these warnings and errors are in different classes).

So I was wondering if anyone saw any blatant errors that I may have missed because I’m new to programming in general.

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Edit: I didn’t originally include the code since it is long, but here is the code giving errors.

Here is “MazeCell.m”:

#import "MazeCell.h"

@implementation MazeCell

@synthesize left;
@synthesize right;
@synthesize down;
@synthesize up;
@synthesize drawCount;
@synthesize row;
@synthesize column;

-(id) init {
    if (self = [super init]) {
        right = MazeCellEdgeWall;
        up = MazeCellEdgeWall;
        left = MazeCellEdgeWall;
        down = MazeCellEdgeWall;
        drawCount = 0;
    }
    return self;
}

- (id)initWithLeft:(MazeCellEdge)newLeft
             right:(MazeCellEdge)newRight
                up:(MazeCellEdge)newUp
              down:(MazeCellEdge)newDown
               row:(NSUInteger)newRow
            column:(NSUInteger)newColumn
{
    if (self = [super init]) {
        left = newLeft;
        right = newRight;
        up = newUp;
        down = newDown;
        drawCount = 0;
        row = newRow;
        column = newColumn;
    }
    return self;
}
@end

Here is MazeView.h:

#import "MazeView.h"
#import "MazeCell.h"
#import "NSMutableArray+Stack.h"

#define kCellSidesSize 80.0

@implementation MazeView

@synthesize maze;
@synthesize controller;
@synthesize interfaceOrientation;

- (id)initWithFrame:(CGRect)frame {
    if (self = [super initWithFrame:frame]) {
        interfaceOrientation = UIInterfaceOrientationPortrait;
        [self setBackgroundColor:[UIColor greenColor]];
        [self setUserInteractionEnabled:YES];
        [self setMaze:[[Maze alloc] initWithSize:MazeSizeMake(4, 6)]];
    }
    return self;
}

- (void)setMaze:(Maze *)newMaze {
    maze = newMaze;
    CGRect newFrame = [self frame];
    newFrame.size = CGSizeMake([newMaze size].width * kCellSidesSize,
                               [newMaze size].height * kCellSidesSize);
    [self setFrame:newFrame];
}

- (void)setInterfaceOrientation:(UIInterfaceOrientation)newOrientation {
    if (interfaceOrientation != newOrientation) {
        interfaceOrientation = newOrientation;
        CGRect oldFrame = [self frame];
        [self setFrame:CGRectMake(oldFrame.origin.y, oldFrame.origin.x,
                                  oldFrame.size.height, oldFrame.size.width)];
        [[self superview] setContentSize:[self frame].size];
    }
}

- (void)setController:(UIViewController *)newController {
    if (controller != newController) {
        controller = newController;
    }
}

- (void)drawRect:(CGRect)rect {
    CGContextRef context = UIGraphicsGetCurrentContext();
    NSUInteger columns = [[self maze] size].width;
    NSUInteger rows = [[self maze] size].height;

    CGContextSetRGBStrokeColor(context, 1.0, 1.0, 1.0, 1.0);
    CGContextSetLineWidth(context, kCellSidesSize - 2.0);
    CGContextSetLineJoin(context, kCGLineJoinRound);
    CGContextSetLineCap(context, kCGLineCapRound);

    BOOL isDrawing = NO;
    MazeCell *aCell;
    NSMutableArray *aStack = [[NSMutableArray alloc] init];
    NSUInteger row = 0;
    NSUInteger column = 0;

    while (YES) {
        aCell = [maze getCellInRow:row andColumn:column ofOrientation:interfaceOrientation];

        if (isDrawing) {
            CGContextAddLineToPoint(context, row * kCellSidesSize + kCellSidesSize / 2.0,
                                          column * kCellSidesSize + kCellSidesSize / 2.0);
        } else {
            isDrawing = YES;
            CGContextMoveToPoint(context,  row * kCellSidesSize + kCellSidesSize / 2.0,
                                        column * kCellSidesSize + kCellSidesSize / 2.0);
        }

        if ([aCell left] == MazeCellEdgeExit && [aCell drawCount] < 1) {
            //Warnings and errors
            [aCell setDrawCount:1];  //Warning
            column--;
        } else if ([aCell right] == MazeCellEdgeExit && [aCell drawCount] < 2) {
            //Warnings and errors
            [aCell setDrawCount:2];  //Warning
            column++;
        } else if ([aCell up] == MazeCellEdgeExit && [aCell drawCount] < 3) {
            //Warnings and errors
            [aCell setDrawCount:3];  //Warning
            row--;
        } else if ([aCell down] == MazeCellEdgeExit && [aCell drawCount] < 4) {
            //Warnings and errors
            [aCell setDrawCount:4];  //Warning
            row++;
        } else if ([aStack count] > 0) {
            aCell = [aStack pop];
            row = [aCell row];       //Warning
            column = [aCell column]; //Warning
            isDrawing = NO;
        } else {
            break;
        }
    }
    CGContextStrokePath(context);
    [aStack release];
}

@end

Again, this is provided to prove that I have coded things. This program works and, as I said, the maze cell methods actually do work, it’s just that Xcode is giving me warnings which I wouldn’t care about, except that it says I haven’t defined MazeCellEdgeExit and so doesn’t compile anymore, but it does compile otherwise.

---

Now this is quite strange. But I have discovered that duplicating the MazeCell.h and MazeCell.m files and renaming them to MzCell.h and MzCell.m, and then replacing every reference to MazeCell with MzCell got this program to run.

Although that opens up more questions than it answers…

Answer 1

Everything looks good to me. Try a clean and build. It’s quite possible that outdated object files are floating around, confusing the compiler or linker.

I haven’t been able to detect a bug that would prevent compilation, although there are a number of apparent memory leaks, such as in setMaze: where you don’t release the old maze. (You definitely allocate a maze in -initWithFrame: so you leak at least that one.) Also, the default setter semantic is “assign”, not “retain” or “copy” — in this case, it would seem that one of the latter two behaviors would make more sense. I realize you’re new to Objective-C, so these are meant by way of constructive feedback, not criticism. 🙂