objective-c - NSString drawInRect:withAttributes:导致“无法识别的选择器发送到实例……”

我得到了一个非常奇怪的结果：一个方法导致了unrecognized selector sent to instance，但根本没有任何结果。
我创建了一个自定义nscontrol子类，在其中，我尝试如下绘制自定义单元格：

- (void)drawRect:(NSRect)dirtyRect {
    NSLog(@"DrawRect entered!");
    [[NSColor grayColor] set];
    [NSBezierPath fillRect:[self bounds]];

    unsigned int i, count = [cells count];
    NSRect cellRect = NSMakeRect(0, 0, ([self bounds]).size.width, cellHeight);
    for (i = 0; i < count; i++) {
        NSLog(@"Drawing cell %d at: %@", i, NSStringFromRect(cellRect));
        MKMenuCell *cell = [cells objectAtIndex:i];
        [cell drawWithFrame:cellRect inView:self];
        cellRect.origin.y += cellHeight;
    }
}

以及NSLog()：

- (void)drawWithFrame:(NSRect)bounds inView:(NSView *)controlView {
    NSLog(@"-drawWithFrame:inView:");
    NSMutableDictionary *strAttribs = [[NSMutableDictionary alloc] init];
    [strAttribs setObject:[NSColor blackColor] forKey:NSFontAttributeName];
    [name drawInRect:bounds withAttributes:strAttribs]; // "unrecognized selector sent ..." is caused by this method call.
}

输出：

2013-03-11 18:46:54.823 MacOverflow[738:a0f] DrawRect entered!
2013-03-11 18:46:54.826 MacOverflow[738:a0f] Drawing cell 0 at: {{0, 0}, {176, 30}}
2013-03-11 18:46:54.826 MacOverflow[738:a0f] -drawWithFrame:inView:
2013-03-11 18:46:54.827 MacOverflow[738:a0f] Drawing cell 1 at: {{0, 30}, {176, 30}}
2013-03-11 18:46:54.828 MacOverflow[738:a0f] -drawWithFrame:inView:
2013-03-11 18:46:54.828 MacOverflow[738:a0f] -[NSCachedWhiteColor screenFontWithRenderingMode:]: unrecognized selector sent to instance 0x100512920
2013-03-11 18:46:54.829 MacOverflow[738:a0f] An uncaught exception was raised
2013-03-11 18:46:54.831 MacOverflow[738:a0f] -[NSCachedWhiteColor screenFontWithRenderingMode:]: unrecognized selector sent to instance 0x100512920
2013-03-11 18:46:54.834 MacOverflow[738:a0f] *** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '-[NSCachedWhiteColor screenFontWithRenderingMode:]: unrecognized selector sent to instance 0x100512920'
*** Call stack at first throw:
(
    0   CoreFoundation                      0x00007fff88c26784 __exceptionPreprocess + 180
    1   libobjc.A.dylib                     0x00007fff858ddf03 objc_exception_throw + 45
    2   CoreFoundation                      0x00007fff88c80110 +[NSObject(NSObject) doesNotRecognizeSelector:] + 0
    3   CoreFoundation                      0x00007fff88bf88ef ___forwarding___ + 751
    4   CoreFoundation                      0x00007fff88bf4a38 _CF_forwarding_prep_0 + 232
    5   AppKit                              0x00007fff89afcfae +[NSStringDrawingTextStorage _fastDrawString:attributes:length:inRect:graphicsContext:baselineRendering:usesFontLeading:usesScreenFont:typesetterBehavior:paragraphStyle:lineBreakMode:boundingRect:padding:scrollable:] + 402
    6   AppKit                              0x00007fff896db539 _NSStringDrawingCore + 1588
    7   MacOverflow                         0x00000001000159b7 -[MKMenuCell drawWithFrame:inView:] + 229
    8   MacOverflow                         0x0000000100015f1e -[MKMenuControl drawRect:] + 595
    9   AppKit                              0x00007fff896d6cc5 -[NSView _drawRect:clip:] + 3390
    10  AppKit                              0x00007fff896d5938 -[NSView _recursiveDisplayAllDirtyWithLockFocus:visRect:] + 1325
    11  AppKit                              0x00007fff896d5ca2 -[NSView _recursiveDisplayAllDirtyWithLockFocus:visRect:] + 2199
    12  AppKit                              0x00007fff896d5ca2 -[NSView _recursiveDisplayAllDirtyWithLockFocus:visRect:] + 2199
    13  AppKit                              0x00007fff896d5ca2 -[NSView _recursiveDisplayAllDirtyWithLockFocus:visRect:] + 2199
    14  AppKit                              0x00007fff896d400a -[NSView _recursiveDisplayRectIfNeededIgnoringOpacity:isVisibleRect:rectIsVisibleRectForView:topView:] + 767
    15  AppKit                              0x00007fff896d3b2c -[NSThemeFrame _recursiveDisplayRectIfNeededIgnoringOpacity:isVisibleRect:rectIsVisibleRectForView:topView:] + 254
    16  AppKit                              0x00007fff896d03de -[NSView _displayRectIgnoringOpacity:isVisibleRect:rectIsVisibleRectForView:] + 2683
    17  AppKit                              0x00007fff89649c0e -[NSView displayIfNeeded] + 969
    18  AppKit                              0x00007fff89611c3b -[NSWindow _reallyDoOrderWindow:relativeTo:findKey:forCounter:force:isModal:] + 1050
    19  AppKit                              0x00007fff896117d2 -[NSWindow orderWindow:relativeTo:] + 94
    20  AppKit                              0x00007fff895dd974 -[NSIBObjectData nibInstantiateWithOwner:topLevelObjects:] + 1726
    21  AppKiProgram received signal:  “SIGABRT”.
t                              0x00007fff895dba91 loadNib + 226
    22  AppKit                              0x00007fff895dafa1 +[NSBundle(NSNibLoading) _loadNibFile:nameTable:withZone:ownerBundle:] + 248
    23  AppKit                              0x00007fff895dadd9 +[NSBundle(NSNibLoading) loadNibNamed:owner:] + 326
    24  AppKit                              0x00007fff895d835b NSApplicationMain + 279
    25  MacOverflow                         0x0000000100000ef9 main + 33
    26  MacOverflow                         0x0000000100000ed0 start + 52
    27  ???                                 0x0000000000000001 0x0 + 1
)
terminate called after throwing an instance of 'NSException'

如您所见，调用了-[MKMenuCell drawWithFrame:inView:]'sMKMenuCell。但其drawWithFrame:inView:语句的输出不会显示。这里发生了什么事？怎么解决？
编辑：我现在意识到，看看gdb的输出，第一次什么都没有出错。这让它变得更加陌生。

最佳答案

发送的错误选择器screenFontWithRenderingMode是nsfont上的一个方法。我打赌你不应该为键的值设置颜色。你应该给它一个字体。