This document provides an overview of table views in iOS apps. It discusses the main components needed, including the table view, table view controller, and data source and delegate classes. It covers common table view tasks like displaying and selecting data, reusing table cells, and making table views editable by adding, removing, and moving rows.

1. Table
Views
in
iOS
Apps
Jussi
Pohjolainen

2. About
Table
Views
• UI
Component
that
presents
data
in
scrollable
list.
Holds
rows
that
may
divided
into
sec1ons
• Many
purposes
– Navigate
data
– Present
data
– Selectable
list
of
opFons
• Two
styles:
plain
or
grouped

3. Plain
Table
View

4. Cells
• Table
view
draws
it’s
rows
using
UITableViewCell
objects
– Can
contain
text,
images
or
other
kind
of
content
– Can
contain
background
view
for
normal
and
selected
states
• Framework
defines
four
cell
types,
with
common
informa1on
– Main
label,
detail
label
and
image
– You
can
define
your
own
cell
type
also

5. Responding
to
SelecFons
• As
always,
UITableView
has
an
delegate
• Delegate
methods
are
called
when
user
clicks
a
row.
Method
receives
the
index
of
row
and
secFon

6. EdiFng
Mode
• Table
views
can
support
edi1ng
mode
– User
can
insert
or
delete
rows,
relocate
them
in
the
table
• When
ediFng
a
sequence
of
messages
are
sent
to
data
source
and
delegate

7. IMPLEMENTING
TABLE
VIEW

8. Classes
Needed
• Table
View
– UITableView
– Manage
selecFons,
scroll
the
table
view,
insert
or
delete
rows
and
selecFons
– UITableView
inherites
UIScrollView,
defines
scrolling
as
default
• Table
View
Controller
– UITableViewController
– Adds
support
for
many
standard
table
related
behaviors.
Minimize
the
amount
of
code
you
have
to
write.
– Subclass
UITableViewController
• Data
Source
and
Delegate
– UITableView
must
have
delegate
and
data
source:
UITableViewDataSource
and
UITableViewDelegate

9. UITableViewDelegate
• Lot’s
of
opFons:
– Configuring
Rows
for
the
Table
View
– Managing
SelecFons
– Modifying
Header
and
Footer
– EdiFng
Table
Rows
• See
UITableViewDelegate
documentaFon
for
all
methods

10. UITableViewDataSource
• Provides
informaFon
about
the
data
model
of
the
table
view
• Configuring
a
Table
View,
required
methods:
– tableView:cellForRowAtIndexPath:
• Returns
the
UITableViewCell
for
row
– tableView:numberOfRowsInSecFon:
• Returns
the
number
of
rows

11. Xcode
Template
• When
creaFng
a
new
UITableViewController,
let
Xcode
create
a
xib
file
for
you
• Xcode
creates
– Class
that
inherites
UITableViewController
– XIB
with
UITableView
– ConnecFons
• dataSource
-­‐>
file
owner
• delegate
-­‐>
file
owner
– Template
code
for
dataSource
and
delegate
methods

12. Data
Source
Required
Methods

13. Reusing
UITableViewCells
• If
one
would
have
large
amount
of
UITableViewCells
in
UITableView,
it
would
take
a
lot
of
memory
• Offscreen
cells
are
put
into
a
pool
of
cells
available
for
reuse
• Instead
of
creaFng
a
new
cell
for
every
request,
the
data
source
first
checks
the
pool
– I
need
a
cell
with
this
reuse
iden1fier
(=
name
of
the
cell
class)
• If
unused
cell,
it
configures
it
with
new
data
and
returns
it
to
the
table
view

14. Reusing

15. NSIndexPath
• The
NSIndexPath
class
represents
the
path
to
a
specific
node
in
a
tree
of
nested
array
collecFons.
This
path
is
known
as
an
index
path.
• Has
two
properFes:
secFon
and
row

16. NavigaFon
and
Table
View
• Follow
paYerns
that
are
common
to
all
navigaFon-­‐based
apps
– Use
data
model
that
has
hierarchical
depth;
arrays,
dicFonary,
some
collecFon
– Array
may
contain
another
array
and
so
on..
• When
user
taps
a
row,
then
– Create
new
table
view
controller,
set
it’s
data
and
push
it
to
navigaFon
controller

17. Simple
Data
Model
Object

18. Push
Content
to
Another
View
Controller

19. EDITABLE
TABLE
VIEW

20. Editable
Table
View
• User
can
add,
delete
or
move
table
rows
• Set
ediFng
property
to
YES
– [[self tableView]
setEditing:YES];
• And
implement
delegate
methods
for
moving
and
deleFng

21. Adding
Rows

22. Removing
Rows

23. Moving
Rows