Q:

How do i read only png files saved in Documents Directory and add it toan Array? 

I am downloading a zip file to Documents directory of iPhone and then Unzipping it there. Now i want to read only png files from there and load it into an Array. How do i do that? 

A:

You would do something like this...
NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);

NSString *documentDirectory = [paths objectAtIndex:0];
NSArray *dirContents = [[NSFileManager defaultManager] directoryContentsAtPath:documentDirectory];

NSMutableArray *array = [NSMutableArray array];

for (NSString *tString in dirContents) {
         if ([tString hasSuffix:@".png"]) {
               [array addObject:string];
     }
}

