iphone - 为什么我的应用程序在我更改框架时偶尔会崩溃？

Question

我有一个自定义的 UISegmentedControl，当我初始化它时，它有时会崩溃。这是不常见的，大约有 1% 的时间(只是不常见到足以通过苹果的“严格”应用程序测试)，即使我在其他三个 View 中有完全相同的代码，它也只会在其中一个特定的 View 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:

- 大多数时候不会发生崩溃。

-即使代码相同，崩溃也只会发生在四个 View Controller 之一上。

- 崩溃只在模拟器中被发现(与此有关？？)不过，这可能只是因为在模拟器中进行的测试比在设备上进行的测试多得多。

-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

完整的错误信息:

* 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

Answer 1

UIControlState 是一个枚举。您正在传递一个指向应该是 UIControlState 的值的指针，但实际上直接使用了指针的值，甚至没有取消引用。

去掉签名中UIControlState参数的指针就OK了。

-(void)setBarColor:(UIColor *)color forState:(UIControlState)state

这将满足 UISegmentedControl 的方法签名:

-(void)setBackgroundImage:(UIImage *)backgroundImage forState:(UIControlState)state barMetrics:(UIBarMetrics)barMetrics