For NSInteger     %d  integer    %ld  long
For CGFloat     %f  float     %.21g  double
NSString *nameOfString = @"content of string";
     NSLog( @"%@" , argument for @);      % is string format specifier, @ is content of string
NSArray *nameOfArray = @[ @"object1", @"object2", @"object3" ];
NSDictionary *nameOfDictionary = @{ @"key1":obj1 , @"key2":obj2 , @"key3":obj3 };