Method returns NSString as nil

Question

I have method which builds NSString and returns it correctly. However if i call the same method from separate thread it returns nil even though my NSString is not nil in line with return.

I get request = nil in "getPhones" method.

"return request" in "createSelectPhonesRequest" ontains valid string.

"getXmlRow" actually builds the string.

+ (void)getUserPhones:(User *)user
{
    NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init];

    [DataManager getPhones:user];

    [pool release];
}

+ (void)getPhones:(User*)user
{
    NSString *request = [XMLBuilder createSelectPhonesRequest:user.NickName];
    NSString *getAddressesResponce = [TrafficManager sendRequest:request];      
}


+(NSString*) createSelectPhonesRequest:(NSString*)nickName
{
    NSString *request;
    NSMutableArray *attributes;
    NSMutableArray *attributesValues;

    /*** root ***/
    attributes = [NSMutableArray new];
    attributesValues = [NSMutableArray new];

    //time
    [attributes addObject:xmlAt.time];
    [attributesValues addObject:[NSDate getXmlFormattedDateFromCurrentDate]];
    //action
    [attributes addObject:xmlAt.action];    
    [attributesValues addObject:xmlAV.selectPhones];


    request = [XMLBuilder getXmlRow:xmlEl.envelop 
                         attributes:attributes 
                   attributesValues:attributesValues 
                              value:nil 
                              close:YES];
    [attributes release];
    [attributesValues release];


    return request;
}


+(NSString*) getXmlRow:(NSString*)element 
               attributes:(NSMutableArray*)attributes 
         attributesValues:(NSMutableArray*)attributesValues 
                    value:(NSString*)value 
                    close:(BOOL)close

{
    //open tag
    NSString* xmlRow = @"<";    
    //tag
    xmlRow = [xmlRow stringByAppendingString:element];
    //attrivutes+values
    if (attributes && attributesValues)
        for (int i=0; i<[attributes count]; i++)
        {
            NSString *attribute = (NSString*) [attributes objectAtIndex:i];
            NSString *attributeValue = (NSString*) [attributesValues objectAtIndex:i];

            xmlRow = [xmlRow stringByAppendingString:@" "];
            xmlRow = [xmlRow stringByAppendingString:(attribute)];      
            xmlRow = [xmlRow stringByAppendingString:@"=\""];
            xmlRow = [xmlRow stringByAppendingString:attributeValue];       
            xmlRow = [xmlRow stringByAppendingString:@"\""];
        }
    //end tag
    xmlRow = [xmlRow stringByAppendingString:@">"];
    //value
    if (value != nil)
        xmlRow = [xmlRow stringByAppendingString:value];
    //close tag
    if (close)
        xmlRow = [xmlRow stringByAppendingString:[self closeElement:element]];
    return xmlRow;
}

http://stackoverflow.com/questions/510269/how-do-i-concatenate-strings-in-objective-c use it how usefull for you — Marios, Nov 21 '11 at 06:51
This should work fine for me either, but it is not. It does only if i run it synchronously without thread. — Misha, Nov 21 '11 at 10:59

score 1 · Answer 1 · answered Nov 21 '11 at 06:13

1

I suspect that you have not created autorelease pool for the thread. Every thread must have it's own autorelease pool.

answered Nov 21 '11 at 06:13

taskinoor

45,586
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I do have autorelease pool. Probably autoreleaseing does the problem. But i tryed to allocate the string but got the same effect. – Misha Nov 21 '11 at 06:18
Is your XML valid for the thread call? Your new edit has almost no similarity with your previous simple example which leaded me to think about autorelease pool. – taskinoor Nov 21 '11 at 06:49
yes it is. i did not post all the createSelectPhonesRequest because there is no need. all the lines in there are the same. Did you notice that all my methods are static? – Misha Nov 21 '11 at 06:51

score 0 · Answer 2 · answered Nov 21 '11 at 05:57

0

I think you should properly Initialize the string like,

NSString *myString = [NSString stringWithString:@"Hello"];

answered Nov 21 '11 at 05:57

EXC_BAD_ACCESS

2,699
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It didn't help. Still i get nil in calling method. – Misha Nov 21 '11 at 06:10
NSString *myString = [[NSString alloc] initWithString:@"Hello"]; //then ur code return [myString autoRelease]; – EXC_BAD_ACCESS Nov 21 '11 at 06:13
Got the same effect. Maybe because my method is static there is some problem. – Misha Nov 21 '11 at 06:19

Method returns NSString as nil

2 Answers2