Question

在编写我的词典以创建CG缩略图时，如果我将值直接映射到int它完美地运行：

 NSDictionary* d = [NSDictionary dictionaryWithObjectsAndKeys:
                       (id)kCFBooleanTrue, kCGImageSourceShouldAllowFloat,
                       (id)kCFBooleanTrue, kCGImageSourceCreateThumbnailWithTransform,
                       (id)kCFBooleanTrue, kCGImageSourceCreateThumbnailFromImageAlways,
                       [NSNumber numberWithInt:56], kCGImageSourceThumbnailMaxPixelSize,
                       nil];
.
.
.
.
.
CGImageRef imref = CGImageSourceCreateThumbnailAtIndex(src, 0, (CFDictionaryRef)d);

现在我希望能够将该值（56）更改为我可以在界面中更改的属性，以便在标题中创建一个int

my.h
int thumbSize;

//within my init method Iinitialize it:
        thumbSize = 56;
//then I change the reference in the dictionary:

    NSDictionary* d = [NSDictionary dictionaryWithObjectsAndKeys:
                       (id)kCFBooleanTrue, kCGImageSourceShouldAllowFloat,
                       (id)kCFBooleanTrue, kCGImageSourceCreateThumbnailWithTransform,
                       (id)kCFBooleanTrue, kCGImageSourceCreateThumbnailFromImageAlways,
                       [NSNumber numberWithInt:thumbSize], kCGImageSourceThumbnailMaxPixelSize,
                       nil];

如果我这样做，它会因以下错误崩溃：

Mar 25 11:39:49 Charles-Romestants-MacBook.local PhotoMosaic[3583] : ImageIO: CGImageSourceCreateWithData data parameter is nil
Mar 25 11:39:49 Charles-Romestants-MacBook.local PhotoMosaic[3583] : ImageIO: CGImageSourceCreateImageAtIndex image source parameter is nil
2013-03-25 11:39:49.197 PhotoMosaic[3583:707] *** -[__NSArrayM insertObject:atIndex:]: object cannot be nil
2013-03-25 11:39:49.201 PhotoMosaic[3583:707] (
    0   CoreFoundation                      0x00007fff912ccb06 __exceptionPreprocess + 198
    1   libobjc.A.dylib                     0x00007fff8bc833f0 objc_exception_throw + 43
    2   CoreFoundation                      0x00007fff9127d27a -[__NSArrayM insertObject:atIndex:] + 282
    3   PhotoMosaic                         0x00000001000023bf -[BlendingView setMosaicImages:] + 1071
    4   PhotoMosaic                         0x0000000100003034 -[Controller createMosaic:] + 84
    5   AppKit                              0x00007fff8ec3d989 -[NSApplication sendAction:to:from:] + 342
    6   AppKit                              0x00007fff8ec3d7e7 -[NSControl sendAction:to:] + 85
    7   AppKit                              0x00007fff8ec3d71b -[NSCell _sendActionFrom:] + 138
    8   AppKit                              0x00007fff8ec3bc03 -[NSCell trackMouse:inRect:ofView:untilMouseUp:] + 1855
    9   AppKit                              0x00007fff8ec3b451 -[NSButtonCell trackMouse:inRect:ofView:untilMouseUp:] + 504
    10  AppKit                              0x00007fff8ec3abcc -[NSControl mouseDown:] + 820
    11  AppKit                              0x00007fff8ec3253e -[NSWindow sendEvent:] + 6853
    12  AppKit                              0x00007fff8ec2e674 -[NSApplication sendEvent:] + 5761
    13  AppKit                              0x00007fff8eb4424a -[NSApplication run] + 636
    14  AppKit                              0x00007fff8eae8c06 NSApplicationMain + 869
    15  PhotoMosaic                         0x0000000100001d52 main + 34
    16  PhotoMosaic                         0x0000000100001d24 start + 52
)

为什么这样，我正在传递NSNumber + numberWithInt一个int ...

[编辑]添加整个方法：

-(void)setMosaicImages:(NSMutableArray *)_mosaicImages
{
    NSLog(@"Entering here in setMosaicImages, we have %lu images",_mosaicImages.count);
    mosaicImages = _mosaicImages;
    CGImageSourceRef source;

    source = CGImageSourceCreateWithData((CFDataRef)[canvasImage TIFFRepresentation], NULL);
    CGImageRef image =  CGImageSourceCreateImageAtIndex(source, 0, NULL);
    CGColorSpaceRef colorspace = CGColorSpaceCreateDeviceRGB();
    CGContextRef ctx = CGBitmapContextCreate(NULL,
                                             CGImageGetWidth(image), CGImageGetHeight(image),
                                             8, CGImageGetWidth(image) * 4,
                                             colorspace, kCGImageAlphaPremultipliedLast);
    CGColorSpaceRelease(colorspace);

    NSDictionary* d = [NSDictionary dictionaryWithObjectsAndKeys:
                       (id)kCFBooleanTrue, kCGImageSourceShouldAllowFloat,
                       (id)kCFBooleanTrue, kCGImageSourceCreateThumbnailWithTransform,
                       (id)kCFBooleanTrue, kCGImageSourceCreateThumbnailFromImageAlways,
                       [NSNumber numberWithInt:thumbSize], kCGImageSourceThumbnailMaxPixelSize,
                       nil];

//thumbSize is declared in.h and initialized in init method with a value of 56 (int thumbSize; then thumbSize = 56; if I change the parameter to literal 56 it works.    
//create NSMUTABLE array with thumbnails for each mosaic image
    mosaicCGThumbs = [[NSMutableArray alloc]initWithCapacity:mosaicCGThumbs.count];
    NSURL* url;
    for(int i=0; i<mosaicImages.count;i++)
    {
        url = [NSURL fileURLWithPath:[(myImageObject *)[mosaicImages objectAtIndex:i] getPath]];
        CGImageSourceRef src = CGImageSourceCreateWithURL((CFURLRef)url, NULL);
        CGImageRef imref = CGImageSourceCreateThumbnailAtIndex(src, 0, (CFDictionaryRef)d);
        [mosaicCGThumbs addObject:imref];
        CGImageRelease(imref);

    }
    CGRect r;
    CGImageRef thumbRef;
    int x_offset=0;
    int y_offset = 0;
    while(y_offset < CGImageGetHeight(image))
    {
        while (x_offset<CGImageGetWidth(image))
        {
            thumbRef = (CGImageRef)[mosaicCGThumbs objectAtIndex:arc4random() % mosaicCGThumbs.count];
            r = CGRectMake(x_offset, y_offset, CGImageGetWidth(thumbRef), CGImageGetHeight(thumbRef));
            CGContextSetBlendMode(ctx, kCGBlendModeCopy);
            CGContextDrawImage(ctx, r, thumbRef);

            x_offset+=CGImageGetWidth(thumbRef);
        }
        x_offset=0;
        y_offset+=56;
    }
    NSLog(@"Finished Drawing Mosaic BG");

    image = CGBitmapContextCreateImage(ctx);
    //
    //    CIImage* newImage = [[[CIImage alloc] initWithCGImage:image] autorelease];
    //    CGImageRelease(image);
    CGContextRelease(ctx);
    canvasImage = [[NSImage alloc] initWithCGImage:image size:NSZeroSize];
    mosaicPresent=YES;
    [self setNeedsDisplay:YES];

  }

为调试目的添加更多信息：

我决定看看与创建的NSDictionary有什么不同，所以

我添加了以下代码和一个断点来检查：

    NSDictionary* d = [NSDictionary dictionaryWithObjectsAndKeys:
                   (id)kCFBooleanTrue, kCGImageSourceShouldAllowFloat,
                   (id)kCFBooleanTrue, kCGImageSourceCreateThumbnailWithTransform,
                   (id)kCFBooleanTrue, kCGImageSourceCreateThumbnailFromImageAlways,
                   [NSNumber numberWithInt:thumbSize], kCGImageSourceThumbnailMaxPixelSize,
                   nil];

NSDictionary* d2 = [NSDictionary dictionaryWithObjectsAndKeys:
                   (id)kCFBooleanTrue, kCGImageSourceShouldAllowFloat,
                   (id)kCFBooleanTrue, kCGImageSourceCreateThumbnailWithTransform,
                   (id)kCFBooleanTrue, kCGImageSourceCreateThumbnailFromImageAlways,
                   [NSNumber numberWithInt:56], kCGImageSourceThumbnailMaxPixelSize,
                   nil];

使用调试器查看它我得到了这个:(看看两者在拇指尾的像素大小的值方面有何不同。将会更多地考虑这一点。

(gdb) po d
{
    kCGImageSourceCreateThumbnailFromImageAlways = 1;
    kCGImageSourceCreateThumbnailWithTransform = 1;
    kCGImageSourceShouldAllowFloat = 1;
    kCGImageSourceThumbnailMaxPixelSize = 0;
}
(gdb) po d2
{
    kCGImageSourceCreateThumbnailFromImageAlways = 1;
    kCGImageSourceCreateThumbnailWithTransform = 1;
    kCGImageSourceShouldAllowFloat = 1;
    kCGImageSourceThumbnailMaxPixelSize = 56;
}

Answer 1

执行此代码时，您确定thumbSize是56吗？这似乎不太可能。

我在您的pastebin中看到您同时拥有-init和-initWithFrame:方法。如果您使用-initWithFrame:初始化对象，则可能未调用-init方法，因此未设置thumbSize的值。这是一个奇怪的怪癖（IMO;其他人可能不同意）-initWithFrame:的标准实现不会调用-init。

Answer 2

好的，谢谢你的帮助：错误甚至比预期的更简单，init方法没有被调用来启动变量，我不得不把它放在initWithFrame中：

- (id)init
{
    self = [super init];
    if (self) {
        // Initialization code here.
        mosaicPresent = NO;
    }

    return self;
}
- (id)initWithFrame:(NSRect)frameRect
{
    self = [super initWithFrame:frameRect];
    invalidateCanvas = YES;
    thumbSize = 56;

    return self;
}

Objective C的字典问题（NSNumber + NumberWithInt）

2 个答案: