このコードは白いテキストを描画しません、なぜですか?
NSMutableParagraphStyle* style = [[NSMutableParagraphStyle alloc] init];
[style setAlignment:NSCenterTextAlignment];
NSFont *font = [NSFont fontWithName:@"System" size:13];
NSDictionary *attrs = [NSDictionary dictionaryWithObjectsAndKeys:style, NSParagraphStyleAttributeName, font, NSFontAttributeName, [NSColor whiteColor], NSForegroundColorAttributeName, nil];
[button.title drawInRect:textRect withAttributes:attrs];