如何让IOS应用从容地崩溃

Posted 2023-04-09

ios SDK中提供了一个现成的函数 NSSetUncaughtExceptionHandler 用来做异常处理，但功能非常有限，而引起崩溃的大多数原因如：内存访问错误，重复释放等错误就无能为力了，因为这种错误它抛出的是Signal，所以必须 要专门做Signal处理。首先定义一个UncaughtExceptionHandler类，.h头文件的代码如下：

#import <UIKit/UIKit.h>
@interface UncaughtExceptionHandler : NSObject

BOOL dismissed;

@end
void InstallUncaughtExceptionHandler();
然后在.mm文件实现InstallUncaughtExceptionHandler()，如下：
void InstallUncaughtExceptionHandler()

signal(SIGABRT, MySignalHandler);
signal(SIGILL, MySignalHandler);
signal(SIGSEGV, MySignalHandler);
signal(SIGFPE, MySignalHandler);
signal(SIGBUS, MySignalHandler);
signal(SIGPIPE, MySignalHandler);


这样，当应用发生错误而产生上述Signal后，就将会进入我们自定义的回调函数MySignalHandler。为了得到崩溃时的现场信息，还可以加入一些获取CallTrace及设备信息的代码，.mm文件的完整代码如下：

#import "UncaughtExceptionHandler.h"
#include <libkern/OSAtomic.h>
#include <execinfo.h>
NSString * const UncaughtExceptionHandlerSignalExceptionName = @"UncaughtExceptionHandlerSignalExceptionName";
NSString * const UncaughtExceptionHandlerSignalKey = @"UncaughtExceptionHandlerSignalKey";
NSString * const UncaughtExceptionHandlerAddressesKey = @"UncaughtExceptionHandlerAddressesKey";
volatile int32_t UncaughtExceptionCount = 0;
const int32_t UncaughtExceptionMaximum = 10;
const NSInteger UncaughtExceptionHandlerSkipAddressCount = 4;
const NSInteger UncaughtExceptionHandlerReportAddressCount = 5;
@implementation UncaughtExceptionHandler
+ (NSArray *)backtrace

void* callstack[128];
int frames = backtrace(callstack, 128);
char **strs = backtrace_symbols(callstack, frames);
int i;
NSMutableArray *backtrace = [NSMutableArray arrayWithCapacity:frames];
for (
i = UncaughtExceptionHandlerSkipAddressCount;
i < UncaughtExceptionHandlerSkipAddressCount +
UncaughtExceptionHandlerReportAddressCount;
i++)

[backtrace addObject:[NSString stringWithUTF8String:strs[i]]];

free(strs);
return backtrace;

- (void)alertView:(UIAlertView *)anAlertView clickedButtonAtIndex:(NSInteger)anIndex

if (anIndex == 0)

dismissed = YES;


- (void)handleException:(NSException *)exception

UIAlertView *alert =
[[[UIAlertView alloc]
initWithTitle:NSLocalizedString(@"Unhandled exception", nil)
message:[NSString stringWithFormat:NSLocalizedString(
@"You can try to continue but the application may be unstable.\\n"
@"%@\\n%@", nil),
[exception reason],
[[exception userInfo] objectForKey:UncaughtExceptionHandlerAddressesKey]]
delegate:self
cancelButtonTitle:NSLocalizedString(@"Quit", nil)
otherButtonTitles:NSLocalizedString(@"Continue", nil), nil]
autorelease];
[alert show];
CFRunLoopRef runLoop = CFRunLoopGetCurrent();
CFArrayRef allModes = CFRunLoopCopyAllModes(runLoop);
while (!dismissed)

for (NSString *mode in (NSArray *)allModes)

CFRunLoopRunInMode((CFStringRef)mode, 0.001, false);


CFRelease(allModes);
NSSetUncaughtExceptionHandler(NULL);
signal(SIGABRT, SIG_DFL);
signal(SIGILL, SIG_DFL);
signal(SIGSEGV, SIG_DFL);
signal(SIGFPE, SIG_DFL);
signal(SIGBUS, SIG_DFL);
signal(SIGPIPE, SIG_DFL);
if ([[exception name] isEqual:UncaughtExceptionHandlerSignalExceptionName])

kill(getpid(), [[[exception userInfo] objectForKey:UncaughtExceptionHandlerSignalKey] intValue]);

else

[exception raise];


@end
NSString* getAppInfo()

NSString *appInfo = [NSString stringWithFormat:@"App : %@ %@(%@)\\nDevice : %@\\nOS Version : %@ %@\\nUDID : %@\\n",
[[NSBundle mainBundle] objectForInfoDictionaryKey:@"CFBundleDisplayName"],
[[NSBundle mainBundle] objectForInfoDictionaryKey:@"CFBundleShortVersionString"],
[[NSBundle mainBundle] objectForInfoDictionaryKey:@"CFBundleVersion"],
[UIDevice currentDevice].model,
[UIDevice currentDevice].systemName,
[UIDevice currentDevice].systemVersion,
[UIDevice currentDevice].uniqueIdentifier];
NSLog(@"Crash!!!! %@", appInfo);
return appInfo;

void MySignalHandler(int signal)

int32_t exceptionCount = OSAtomicIncrement32(&UncaughtExceptionCount);
if (exceptionCount > UncaughtExceptionMaximum)

return;

NSMutableDictionary *userInfo =
[NSMutableDictionary
dictionaryWithObject:[NSNumber numberWithInt:signal]
forKey:UncaughtExceptionHandlerSignalKey];
NSArray *callStack = [UncaughtExceptionHandler backtrace];
[userInfo
setObject:callStack
forKey:UncaughtExceptionHandlerAddressesKey];
[[[[UncaughtExceptionHandler alloc] init] autorelease]
performSelectorOnMainThread:@selector(handleException:)
withObject:
[NSException
exceptionWithName:UncaughtExceptionHandlerSignalExceptionName
reason:
[NSString stringWithFormat:
NSLocalizedString(@"Signal %d was raised.\\n"
@"%@", nil),
signal, getAppInfo()]
userInfo:
[NSDictionary
dictionaryWithObject:[NSNumber numberWithInt:signal]
forKey:UncaughtExceptionHandlerSignalKey]]
waitUntilDone:YES];

void InstallUncaughtExceptionHandler()

signal(SIGABRT, MySignalHandler);
signal(SIGILL, MySignalHandler);
signal(SIGSEGV, MySignalHandler);
signal(SIGFPE, MySignalHandler);
signal(SIGBUS, MySignalHandler);
signal(SIGPIPE, MySignalHandler);


在应用自身的 didFinishLaunchingWithOptions 前，加入一个函数：

- (void)installUncaughtExceptionHandler

InstallUncaughtExceptionHandler();


最后，在 didFinishLaunchingWithOptions 中加入这一句代码就行了：

[self InstallUncaughtExceptionHandler];

现在，基本上所有崩溃都能Hold住了。崩溃时将会显示出如下的对话框： 参考技术A 从容的崩溃? 崩溃很容易, 写个数组定义一个元素, 然后下一个步骤去访问array, 程序立马就崩溃

显示单元部分明智地导致 iOS 应用程序崩溃

【中文标题】显示单元部分明智地导致 iOS 应用程序崩溃

【英文标题】：Display cell section wise crashes iOS app

【发布时间】：2013-11-18 09:40:48

【问题描述】：

我有Tableview，其中包含从A 到Z 的部分（我动态计算的部分数量不固定）

我想这样显示： : 我的数组值：msg_array=["AajKaCatch","AajKaItem","Anari","Big C Mobiles","Big Flix","BigRock","caksonflowers, ...."]

当我尝试在cellForRowAtIndexPath 中这样显示时，它会显示NSInvalidArgumentException

cell.textLabel.text=[[[msg_array objectAtIndex:indexPath.section] objectAtIndex:indexPath.row] objectForKey:@"Merchant_Name"];

请帮助并提前致谢。

【问题讨论】：

msg_array 仅包含字符串对象。它应该包含 NSArray 的对象，其中将包含 NSDictionary 类型的对象。

【参考方案1】：

你的数组是这样的：

arrayobject,object,object,object,object;

在这种情况下，你不能使用like：

[[msg_array objectAtIndex:indexPath.section] objectAtIndex:indexPath.row]

因为要实现这样一个，[msg_array objectAtIndex:indexPath.section] 应该返回一个数组。

所以实现这个，你需要这样尝试：

arrayarrayobjects starts with 'A',arrayobjects starts with 'B',arrayobjects starts with 'C';

【讨论】：

-(void)createAlphabetArray NSMutableArray *tempFirstLetterArray = [[NSMutableArray alloc] init]; for (int i = 0; i < [msg_array count]; i++) NSMutableArray *temp=[[NSMutableArray alloc] init]; NSString *letterString = [[[msg_array objectAtIndex:i] objectForKey:@"Merchant_Name"] substringToIndex:1]; if (![tempFirstLetterArray containsObject:[letterString uppercaseString]]) [tempFirstLetterArray addObject:letterString]; [temp addObject:[[msg_array objectAtIndex:i] objectForKey:@"Merchant_Name"]];

你说得对，但是如何在我的数组中添加元素？以上是我写的代码，但只添加了字符的第一个元素

@Krunal：在你的代码中，当它找到一个新字符时，if 块将为真，在所有其他情况下它将为假。所以它不会添加其他对象

那么，我该如何添加呢？

【参考方案2】：

当你这样做时：

[[[msg_array objectAtIndex:indexPath.section] objectAtIndex:indexPath.row] objectForKey:@"Merchant_Name"];

您正在访问 msg_array 的元素，就好像它是一个 NSArray，其中包含一个 NSDictionary。

但是，在 msg_array 内部你只有NSStrings。

您尝试访问的结构是：

NSArray -> NSArray -> NSDictionary

你有

NSArray -> NSString

【讨论】：

你说得对，但是如何在我的数组中添加元素？下面是我写的代码，但它只添加了字符的第一个元素

-(void)createAlphabetArray NSMutableArray *tempFirstLetterArray = [[NSMutableArray alloc] init]; for (int i = 0; i < [msg_array count]; i++) NSMutableArray *temp=[[NSMutableArray alloc] init]; NSString *letterString = [[[msg_array objectAtIndex:i] objectForKey:@"Merchant_Name"] substringToIndex:1]; if (![tempFirstLetterArray containsObject:[letterString uppercaseString]]) [tempFirstLetterArray addObject:letterString]; [temp addObject:[[msg_array objectAtIndex:i] objectForKey:@"Merchant_Name"]];

【参考方案3】：

我使用 FKRSearchBarTableViewController 对联系信息和其他类似的事情做了同样的事情，请参阅链接，下面是我的 FKRSearchBarTableViewController 代码

    - (id)initWithSectionIndexes:(BOOL)showSectionIndexes withDataSource:(NSArray*) dataSource withControllerId:(int) ControllerId forGroup:(int)groupId

if ((self = [super initWithNibName:nil bundle:nil])) 
    self.title = @"Search Bar";
    NSLog(@"%d",groupId);
    _groupID = groupId;
    _controllerId = ControllerId;

    _showSectionIndexes = showSectionIndexes;

    _famousPersons = [[NSMutableArray alloc]initWithArray:dataSource];
    if (showSectionIndexes) 
        UILocalizedIndexedCollation *collation = [UILocalizedIndexedCollation currentCollation];

        NSMutableArray *unsortedSections = [[NSMutableArray alloc] initWithCapacity:[[collation sectionTitles] count]];
        for (NSUInteger i = 0; i < [[collation sectionTitles] count]; i++) 
            [unsortedSections addObject:[NSMutableArray array]];
        
        if(ControllerId == 5)
        
        for (Person *personName in self.famousPersons) 

               // NSInteger index = [collation sectionForObject:[personName objectForKey:@"FirstName"] collationStringSelector:@selector(description)];
            NSLog(@"%@",personName.firstName);
            NSInteger index = [collation sectionForObject:personName.firstName collationStringSelector:@selector(description)];
                [[unsortedSections objectAtIndex:index] addObject:personName];
        
        
        else
        
            for (NSDictionary *personName in self.famousPersons) 

                 NSInteger index = [collation sectionForObject:[personName objectForKey:@"FirstName"] collationStringSelector:@selector(description)];

                [[unsortedSections objectAtIndex:index] addObject:personName];
            

        

        NSMutableArray *sortedSections = [[NSMutableArray alloc] initWithCapacity:unsortedSections.count];
        for (NSMutableArray *section in unsortedSections) 
            [sortedSections addObject:[NSMutableArray arrayWithArray:[collation sortedArrayFromArray:section collationStringSelector:@selector(description)]]];
        

        self.sections = [NSMutableArray arrayWithArray:sortedSections];

    

【参考方案4】：

为了让列表更加动态，解决方案应该是

// given NSArray names = your full list of name
//       NSArray indexes = your list of index

NSMutableArray *nameSections = [NSMutableArray arrayWithCapacity:26];
NSMutableArray *filteredIndexes = [NSMutableArray arrayWithCapacity:26];

for (NSString *index in indexes) 

    NSPredicate *predicate = [NSPredicate predicateWithFormat:
                              @"SELF beginswith[c] %@",index];
    NSArray *filterNames = [names filteredArrayUsingPredicate:predicate];

    if(filterNames.count>0)
        [nameSections addObject:filterNames];
        [filteredIndexes addObject:index];
    



NSLog(@"filteredIndexes %@",filteredIndexes);
NSLog(@"nameSections %@",nameSections);


numOfSection = nameSections.count
numOfRow = [[numOfSection indexOfObject:section]count];
name = [[numOfSection indexOfObject:section]] indexOfObject:row];


// print log
//given indexes array a~z

names (
"a_string",
"a_string2",
"b_string",
"b_string2"
)

filteredIndexes (
a,
b
)

nameSections (
    (
    "a_string",
    "a_string2"
    ),
    (
    "b_string",
    "b_string2"
    )
)