uiimageview gets nil and hence code crashes - iphone

Question

in this block of code my uiimageview always get nil.as a result the code crashes.i can t figure out where is the uiimageview getting nil.in this code self refers to uitableviewcell.
the code crashes in the code where i am inserting the imageview to the array.is this a problem of memory retain?
MyAppDelegate *appDelegate =(myAppDelegate *)[[UIApplication sharedApplication]delegate];
UIImageView *profileImageView;
UILabel *tweetLabel;
UILabel *timeLabel;
UILabel *profileNameLabel;
UIView *message;
if(self==nil)
{
profileImageView = [[UIImageView alloc] initWithFrame:CGRectZero];
profileImageView.backgroundColor= [UIColor clearColor];
profileImageView.tag = 1;
tweetLabel = [[UILabel alloc] initWithFrame:CGRectZero];
tweetLabel.backgroundColor = [UIColor clearColor];
tweetLabel.tag = 2;
tweetLabel.numberOfLines = 3;
tweetLabel.lineBreakMode = UILineBreakModeWordWrap;
tweetLabel.font = [UIFont systemFontOfSize:10.0];
tweetLabel.textColor=[UIColor blackColor];
timeLabel = [[UILabel alloc] initWithFrame:CGRectZero];
timeLabel.backgroundColor = [UIColor clearColor];
timeLabel.tag = 3;
timeLabel.numberOfLines = 1;
timeLabel.lineBreakMode = UILineBreakModeWordWrap;
timeLabel.font = [UIFont systemFontOfSize:12.0];
timeLabel.textColor=[UIColor blackColor];
profileNameLabel = [[UILabel alloc] initWithFrame:CGRectZero];
profileNameLabel.backgroundColor = [UIColor clearColor];
profileNameLabel.tag = 4;
profileNameLabel.numberOfLines = 1;
profileNameLabel.lineBreakMode = UILineBreakModeWordWrap;
profileNameLabel.font = [UIFont boldSystemFontOfSize:14.0];
profileNameLabel.textColor=[UIColor blackColor];
message = [[UIView alloc] initWithFrame:CGRectMake(0.0, 0.0, self.frame.size.width, self.frame.size.height)];
message.tag = 0;
[message addSubview:profileImageView];
[message addSubview:tweetLabel];
[message addSubview:timeLabel];
[message addSubview:profileNameLabel];
[self addSubview:message];
}
else{
tweetLabel = (UILabel *)[[self.contentView viewWithTag:0]viewWithTag:2];
timeLabel = (UILabel *)[[self.contentView viewWithTag:0]viewWithTag:3];
profileNameLabel = (UILabel *)[[self.contentView viewWithTag:0]viewWithTag:4];
profileImageView = (UIImageView *)[self.contentView viewWithTag:1];
NSLog(#" profileImageView %#",profileImageView);
}
NSString *tweet=[tweetObject tweet];
NSString *profileName=[tweetObject author];
NSString *time=[tweetObject time];
CGSize textSize = [tweet sizeWithFont:[UIFont systemFontOfSize:14.0] constrainedToSize:CGSizeMake(240.0f, 480.0f) lineBreakMode:UILineBreakModeWordWrap];
CGSize timeSize = [time sizeWithFont:[UIFont systemFontOfSize:14.0] constrainedToSize:CGSizeMake(240.0f, 480.0f) lineBreakMode:UILineBreakModeWordWrap];
CGSize profileNameSize = [profileName sizeWithFont:[UIFont boldSystemFontOfSize:14.0] constrainedToSize:CGSizeMake(240.0f, 480.0f) lineBreakMode:UILineBreakModeWordWrap];
profileImageView.frame = CGRectMake(5,self.frame.size.height/2, 44, 44);
NSLog(#" profileImageView %#",profileImageView);
tweetLabel.frame = CGRectMake(54, profileImageView.frame.size.width, 240,25);
timeLabel.frame = CGRectMake(180, 5.0f, 100, timeSize.height);
profileNameLabel.frame = CGRectMake(54,5, 150, profileNameSize.height);
tweetLabel.text=tweet;
timeLabel.text=time;
profileNameLabel.text=profileName;
profileImageView.image = [[UIImage imageNamed:#"fbdefaultProfile.gif"]retain];
NSLog(#" myArray WILL FILL WITH THIS ELEMNTS %# %# %# ",profileImageView,[tweetObject imageURL],#"fbdefaultProfile.gif");
NSArray *myArray = [NSArray arrayWithObjects:profileImageView,[tweetObject imageURL],#"fbdefaultProfile.gif",nil];
NSLog(#" myArray %#",myArray);
NSLog(#"%# myArray ",myArray);
[appDelegate performSelectorInBackground:#selector(updateImageViewInBackground:) withObject:myArray];
}
return;

Answer 1

if(self==nil)
{
what is this.. I think it should be
if(self!=nil)
{
and if it is fine then why are you adding subview to a nill
if(self==nil)
{
//your code .....
//and then you are adding sub view to a nil which is useless
[self addSubview:message];
}

Answer 2

The issue could be in the below line of code.
profileImageView = (UIImageView *)[self.contentView viewWithTag:1];
May be you don't have the an view with tag id 1;
plz check against nil after getting the view from viewWithTag.
if([self.contentView viewWithTag:1] != nil)
{
profileImageView = (UIImageView *)[self.contentView viewWithTag:1];
}