我有一个自定义的UISegmentedControl，当我初始化它时，它有时会崩溃。这种情况并不常见，大约有1％的时间，（只是不常见，通过苹果公司的“严格”应用程序测试），即使我在其他三个视图中使用了完全相同的代码，但它只会在其中一个特定的视图中崩溃。
代码：
NSArray *providers = [[NSArray alloc] initWithObjects:@"All", @"Soon", @"Attn", @"Late", @"Done", nil]; //categories for segmented control
FancySegmentedControl *fancy = [[FancySegmentedControl alloc] initWithItems:providers];
fancy.backgroundColor = [UIColor clearColor]; //change bg color
fancy.frame = CGRectMake(11, 86, 263, 29); //lldb crashes here
[fancy setBackgroundColor:[UIColor colorWithRed:42/255.0f
green:82/255.0f
blue:164/255.0f alpha:1] forState:UIControlStateNormal];
所以，我的症状是：
-Crash大部分时间都不会发生。
-Crash只发生在四个视图控制器之一上，即使代码相同。
-Crash只在模拟器中被注意到（与此有关吗？）这可能是因为测试在模拟器中比在设备上发生的要多得多。
- 我的项目使用ARC。
FancySegmentedControl的代码如下：
@interface FancySegmentedControl : UISegmentedControl
{
UIColor *bgNotSelected;
UIColor *bgSelected;
UIColor *barNotSelected;
UIColor *barSelected;
}
-(void)setBackgroundColor:(UIColor *)color forState:(UIControlState)state;
-(void)setBarColor:(UIColor *)color forState:(UIControlState)state;
-(void)setTextAttributes:(NSDictionary *)attrs forState:(UIControlState) state;
@end
@implementation FancySegmentedControl
- (id)initWithItems:(NSArray *)items
{
self = [super initWithItems:items];
bgSelected = [UIColor blueColor];
bgNotSelected = [UIColor whiteColor];
barNotSelected = [UIColor lightGrayColor];
barSelected = [UIColor orangeColor];
self.selectedSegmentIndex = 0;
if (self) {
//change text stuff
NSDictionary *attributes = [NSDictionary dictionaryWithObjectsAndKeys:
[UIFont boldSystemFontOfSize:17], UITextAttributeFont,
[UIColor blackColor], UITextAttributeTextColor,
nil];
[self setTitleTextAttributes:attributes forState:UIControlStateNormal];
NSDictionary *highlightedAttributes = [NSDictionary dictionaryWithObject:[UIColor whiteColor] forKey:UITextAttributeTextColor];
[self setTitleTextAttributes:highlightedAttributes forState:UIControlStateHighlighted];
//set all dividers to nothing
UIView *yourView = [[UIView alloc] initWithFrame:CGRectMake(0, 0, 1, 30)];
UIGraphicsBeginImageContext(yourView.bounds.size);
[yourView.layer renderInContext:UIGraphicsGetCurrentContext()];
UIImage *image = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
[self setDividerImage:image
forLeftSegmentState:UIControlStateNormal
rightSegmentState:UIControlStateNormal
barMetrics:UIBarMetricsDefault];
[self setDividerImage:image
forLeftSegmentState:UIControlStateSelected
rightSegmentState:UIControlStateNormal
barMetrics:UIBarMetricsDefault];
[self setDividerImage:image
forLeftSegmentState:UIControlStateNormal
rightSegmentState:UIControlStateSelected
barMetrics:UIBarMetricsDefault];
yourView = [[UIView alloc] initWithFrame:CGRectMake(0, 0, 40, 30)];
yourView.backgroundColor = bgNotSelected;
UIView *barView = [[UIView alloc] initWithFrame:CGRectMake(0, yourView.frame.size.height - 3, 40, 3)];
barView.backgroundColor = barNotSelected;
[yourView addSubview:barView];
UIGraphicsBeginImageContext(yourView.bounds.size);
[yourView.layer renderInContext:UIGraphicsGetCurrentContext()];
image = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
UIImage *normalBackgroundImage = image;
[self setBackgroundImage:normalBackgroundImage
forState:UIControlStateNormal
barMetrics:UIBarMetricsDefault];
yourView.backgroundColor = bgSelected;
barView = [[UIView alloc] initWithFrame:CGRectMake(0, yourView.frame.size.height - 3, 40, 3)];
barView.backgroundColor = barSelected;
[yourView addSubview:barView];
UIGraphicsBeginImageContext(yourView.bounds.size);
[yourView.layer renderInContext:UIGraphicsGetCurrentContext()];
image = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
UIImage *selectedBackgroundImage = image;
[self setBackgroundImage:selectedBackgroundImage
forState:UIControlStateSelected
barMetrics:UIBarMetricsDefault];
}
return self;
}
-(void)setBackgroundColor:(UIColor *)color forState:(UIControlState)state
{
UIColor *barColor;
if (state == UIControlStateSelected)
{
bgSelected = color;
barColor = barSelected;
}
else
{
bgNotSelected = color;
barColor = barNotSelected;
}
UIView *yourView = [[UIView alloc] initWithFrame:CGRectMake(0, 0, 40, 30)];
yourView.backgroundColor = color;
UIView *barView = [[UIView alloc] initWithFrame:CGRectMake(0, yourView.frame.size.height - 3, 40, 3)];
barView.backgroundColor = barColor;
[yourView addSubview:barView];
UIGraphicsBeginImageContext(yourView.bounds.size);
[yourView.layer renderInContext:UIGraphicsGetCurrentContext()];
UIImage *image = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
[self setBackgroundImage:image
forState:state
barMetrics:UIBarMetricsDefault];
}
-(void)setBarColor:(UIColor *)color forState:(UIControlState)state
{
UIColor *bgColor;
if (state == UIControlStateSelected)
{
barSelected = color;
bgColor = bgSelected;
}
else
{
barNotSelected = color;
bgColor = bgNotSelected;
}
UIView *yourView = [[UIView alloc] initWithFrame:CGRectMake(0, 0, 40, 30)];
yourView.backgroundColor = bgColor;
UIView *barView = [[UIView alloc] initWithFrame:CGRectMake(0, yourView.frame.size.height - 3, 40, 3)];
barView.backgroundColor = color;
[yourView addSubview:barView];
UIGraphicsBeginImageContext(yourView.bounds.size);
[yourView.layer renderInContext:UIGraphicsGetCurrentContext()];
UIImage *image = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
[self setBackgroundImage:image
forState:state
barMetrics:UIBarMetricsDefault];
}
-(void)setTextAttributes:(NSDictionary *)attrs forState:(UIControlState) state
{
if (state == UIControlStateSelected)
{
//in case user mistakes the states
state = UIControlStateHighlighted;
}
[self setTitleTextAttributes:attrs forState:state];
}
/*
// Only override drawRect: if you perform custom drawing.
// An empty implementation adversely affects performance during animation.
- (void)drawRect:(CGRect)rect
{
// Drawing code
}
*/
@end
完整的错误消息：
* thread #1: tid = 0x1f03, 0x0134609b libobjc.A.dylib`objc_msgSend + 15, stop reason = EXC_BAD_ACCESS (code=2, address=0xb0000008)
frame #0: 0x0134609b libobjc.A.dylib`objc_msgSend + 15
frame #1: 0x0059bcd5 UIKit`-[UISegmentedControl _setBackgroundImage:forState:barMetrics:] + 148
frame #2: 0x0059bd69 UIKit`-[UISegmentedControl setBackgroundImage:forState:barMetrics:] + 73
frame #3: 0x0004f9f5 Services`-[FancySegmentedControl setBarColor:forState:](self=0x0ea5d740, _cmd=0x000518fd, color=0x08db4630, state=0x00000004) + 1141 at FancySegmentedControl.m:135
frame #4: 0x0000538c Services`-[ServicesViewController fixSearchBar](self=0x07f791a0, _cmd=0x0005170b) + 1132 at ServicesViewController.m:174
frame #5: 0x00003f38 Services`-[ServicesViewController viewDidLoad](self=0x07f791a0, _cmd=0x017fe1dd) + 616 at ServicesViewController.m:49
frame #6: 0x0056964e UIKit`-[UIViewController view] + 184
frame #7: 0x00569941 UIKit`-[UIViewController contentScrollView] + 36
frame #8: 0x0057b47d UIKit`-[UINavigationController _computeAndApplyScrollContentInsetDeltaForViewController:] + 36
frame #9: 0x0057b66f UIKit`-[UINavigationController _layoutViewController:] + 43
frame #10: 0x0057b93b UIKit`-[UINavigationController _startTransition:fromViewController:toViewController:] + 303
frame #11: 0x0057c3df UIKit`-[UINavigationController _startDeferredTransitionIfNeeded] + 288
frame #12: 0x0057c561 UIKit`-[UINavigationController __viewWillLayoutSubviews] + 33
frame #13: 0x006984ca UIKit`-[UILayoutContainerView layoutSubviews] + 222
frame #14: 0x004e2301 UIKit`-[UIView(CALayerDelegate) layoutSublayersOfLayer:] + 145
frame #15: 0x019b8e72 CoreFoundation`-[NSObject performSelector:withObject:] + 66
frame #16: 0x003c292d QuartzCore`-[CALayer layoutSublayers] + 266
frame #17: 0x003cc827 QuartzCore`CA::Layer::layout_if_needed(CA::Transaction*) + 231
frame #18: 0x00352fa7 QuartzCore`CA::Context::commit_transaction(CA::Transaction*) + 377
frame #19: 0x00354ea6 QuartzCore`CA::Transaction::commit() + 374
frame #20: 0x00354580 QuartzCore`CA::Transaction::observer_callback(__CFRunLoopObserver*, unsigned long, void*) + 80
frame #21: 0x0198b9ce CoreFoundation`__CFRUNLOOP_IS_CALLING_OUT_TO_AN_OBSERVER_CALLBACK_FUNCTION__ + 30
frame #22: 0x01922670 CoreFoundation`__CFRunLoopDoObservers + 384
frame #23: 0x018ee4f6 CoreFoundation`__CFRunLoopRun + 1174
frame #24: 0x018eddb4 CoreFoundation`CFRunLoopRunSpecific + 212
frame #25: 0x018edccb CoreFoundation`CFRunLoopRunInMode + 123
frame #26: 0x01b49879 GraphicsServices`GSEventRunModal + 207
frame #27: 0x01b4993e GraphicsServices`GSEventRun + 114
frame #28: 0x004a3a9b UIKit`UIApplicationMain + 1175
frame #29: 0x000036d0 Services`main(argc=1, argv=0xbffff214) + 80 at main.m:16
frame #30: 0x000025e5 Services`start + 53
答案 0 :(得分：2)
UIControlState是一个枚举。您正在传递一个指向应该是UIControlState的值的指针，但实际上指针的值是直接使用的，甚至不会被解引用。
从签名中的UIControlState参数中删除指针，您就可以了。
-(void)setBarColor:(UIColor *)color forState:(UIControlState)state
这将符合UISegmentedControl的方法签名：
-(void)setBackgroundImage:(UIImage *)backgroundImage forState:(UIControlState)state barMetrics:(UIBarMetrics)barMetrics
答案 1 :(得分：0)
你是否尝试过在开启僵尸的情况下运行它？
EXC_BAD_ACCESS主要发生是因为你正试图对已经被释放的内存做一些事情，现在那些东西就是垃圾。
看起来像你的代码：
frame #1: 0x0059bcd5 UIKit`-[UISegmentedControl _setBackgroundImage:forState:barMetrics:] + 148
在出现此错误之前，我们是否看到了最后一件事。
在这里放一个断点并检查参数是否真实等等。或者
您只看到此崩溃的原因有时可能与内存使用有关。您的代码，模拟器，设备等中的其他内容会导致内存被清理并重新使用。无论出于何种原因，解除分配器大部分时间都不会被调用，因此即使根据程序中的语义，它也不一定必须存在于该内存块中的指针仍然有效。在其他更紧张的情况下，可能正在回收内存，运行解除分配器，现在系统知道该内存已经返回到系统的分配堆，所以当你试图摆弄它时会引发异常。