flexBox

                                   React Native FlexBox
Flexbox : Flexbox works the same way in React Native as it does in CSS on the web, with a few exceptions.
           The defaults are different, with flexDirection defaulting to column instead of row, alignContent
           defaulting to flex-start instead of stretch, flexShrink defaulting to 0 instead of 1, 
           the flex parameter only supporting a single number.
       Name                         Type
1 flexDirection                 row , row-reverse , column , column-reverse .
2 alignItems                    flex-start , flex-end , center , stretch , baseline .
3 justifyContent                flex-start , flex-end , center , space-between , space-around.
4 alignSelf                     auto , flex-start , flex-end , center , stretch , baseline . 
5 alignContent                  flex-start , flex-end , center ,stretch , space-between , space-around.
6 flexWrap                      wrap , nowrap .
7 flexBasis                     Default Value is 0 , we need to assign the value for flexBasis  .
8 flexGrow                      Default Value is 0 , we need to assign the value for flexGrow .
9 flexShrink                    Default Value is 0 , we need to assign the value for flexShrink .
10 width                        Default Value is auto , pixels , percentage, we need to assign the value for width .
11 height                       Default Value is auto ,  pixel units, rather than percents, we need to assign the value for height .
12 position                     relative , absolute .