Question

i have the following code in my application:

NSArray *lstAttributes = [conditionAttribute componentsSeparatedByString:cstrSystemUIConfigurationAttributeConditionSeparator],
    *lstValues = [conditionValue componentsSeparatedByString:cstrSystemUIConfigurationAttributeConditionSeparator],
    *lstValueTypes = [conditionValueType componentsSeparatedByString:cstrSystemUIConfigurationAttributeConditionSeparator];

if([lstAttributes count] != [lstValues count] ||
   [lstAttributes count] != [lstValueTypes count]) return NO;

BOOL bResult = YES;
NSLog(@"attributes amount - %u", [lstAttributes count]);
for(uint i = 0; i < [lstAttributes count]; i ++)
{
    NSLog(@"counter: %u", i);
    SystemUIConfigurationAttributeCondition *condition = [SystemUIConfigurationAttributeCondition new];

    condition.conditionAttribute = [lstAttributes objectAtIndex:i];
    condition.conditionValue = [lstValues objectAtIndex:i];
    condition.conditionValueType = [lstValueTypes objectAtIndex:i];

    bResult &= [self checkCondition:condition forOwner:owner];

    FreeObject(&condition);

    if(!bResult) break;
}

return bResult;

everything is fine in “debug” configuration. but once i switch it to “release” i face the endless loop. console shows me the following: attributes amount – 2, counter: 0, counter: 1, counter: 1, counter: 1, counter: 1, counter: 1, counter: 1, …… etc.

i tried to use different “for” and “while” operators, but nothing of that worked correctly. the loop still can’t be stopped.

has anyone faced the same problem before?

Answer 1

workaround for this bug as promised:

at first i tried to use code blocks to enumerate all objects in a list instead of “for” loop.

__block BOOL bResult = YES;
[lstAttributes enumerateObjectsUsingBlock:^(id obj, NSUInteger idx, BOOL *stop)
{
    SystemUIConfigurationAttributeCondition *condition = [SystemUIConfigurationAttributeCondition new];

    condition.conditionAttribute = [lstAttributes objectAtIndex:idx];
    condition.conditionValue = [lstValues objectAtIndex:idx];
    condition.conditionValueType = [lstValueTypes objectAtIndex:idx];

    bResult &= [self checkCondition:condition forOwner:owner];

    FreeObject(&condition);

    if(!bResult) *stop = YES;
}];

but i got a crash on second iteration. “lstValues” and “lstValueTypes” pointers suddenly changed their values and application received EXC_BAD_ACCESS. possibly usage of 3 arrays while enumerating only 1 of them is not a good idea. debugger shows that enumeration is performed on the same thread, but 2 of 3 arrays are corrupted by the moment of 2nd iteration.

so i decided to split up my initial loop into 2 parts:

1. prepare a list of conditions
2. check each condition.

first is a usual “for” loop, second – ‘enumerateObjectsUsingBlock:” method of NSArray class. so the final code looks like:

NSArray *lstAttributes = [conditionAttribute componentsSeparatedByString:cstrSystemUIConfigurationAttributeConditionSeparator],
    *lstValues = [conditionValue componentsSeparatedByString:cstrSystemUIConfigurationAttributeConditionSeparator],
    *lstValueTypes = [conditionValueType componentsSeparatedByString:cstrSystemUIConfigurationAttributeConditionSeparator];

if([lstAttributes count] != [lstValues count] ||
   [lstAttributes count] != [lstValueTypes count]) return NO;

NSMutableArray *lstConditions = [NSMutableArray new];
for(uint i = 0; i < [lstAttributes count]; i ++)
{
    SystemUIConfigurationAttributeCondition *condition = [SystemUIConfigurationAttributeCondition new];

    condition.conditionAttribute = [lstAttributes objectAtIndex:i];
    condition.conditionValue = [lstValues objectAtIndex:i];
    condition.conditionValueType = [lstValueTypes objectAtIndex:i];

    [lstConditions addObject:condition];
    FreeObject(&condition);
}

__block BOOL bResult = YES;
[lstConditions enumerateObjectsUsingBlock:^(id obj, NSUInteger i, BOOL *stop) 
{
    if([self checkCondition:[lstConditions objectAtIndex:i] forOwner:owner] == NO)
    {
        bResult = NO;
        *stop = YES;
    }
}];

FreeObject(&lstConditions);

return bResult;

this code works.

i would appreciate if anyone can explain the behavior of my initial loop.