iOS Can you help me understand this line of code?

[Glama]

Hi,
I came across the code below in a book on iphone development:

- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section {

[some code here]

return rows;
}

I dont understand the first line. I understand from the accompanying text in the book that numberOfRowsInSection is the name of the method, so I guess the rest of the line means that it accepts a NSInteger which it refers to as "section". But the first half of the line baffles me. Since the method returns a variable called "rows", I assume that is an integer so Im thinking the "NSInteger" at the beginning of the line specifies the return type. So what is the "tableviewUITableView *)tableView" part for? What does it specify?

Phil

 

[Troglodyte]

- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section {

The method returns an NSInteger and takes two parameters - one is a pointer to a UITableView object, the other is an NSInteger indicating the section in that UITableView that you are to return the number of rows of.

 

[Glama]

Thanks Troglodyte.
So one parameter comes before the method name, and one comes after. As a newbie to objective-c, that seems so odd. Any way to make sense of that? What if it took 3 input parameters? Where would the next one go?

 

[FarSeide]

- (NSInteger) = Return Type
tableView: = Method Name
(UITableView *) = Data Type it accepts (In this case it accepts a pointer to a UITableView)
tableView = Parameter Name
numberOfRowsInSection: = Method Name with Second Parameter
(NSInteger) = Data Type it accepts (In this case it accets NSInteger which is a wrapper class for int)
section = Parameter Name

*if there was a third parameter, it would look like this...
{

- (NSInteger)tableViewUITableView *)tableView numberOfRowsInSectionNSInteger)section someOtherParameter: (NSInteger) someOtherInteger {

 

[PhoneyDeveloper]

Glama, you need to get a book on learning Objective-C and another one on learning iPhone development. You will learn more quickly that way.

 

[lloyddean]

Thanks Troglodyte.
So one parameter comes before the method name, and one comes after. As a newbie to objective-c, that seems so odd. Any way to make sense of that? What if it took 3 input parameters? Where would the next one go?

Actually the name of the function is 'tableView:numberOfRowsInSection:' and takes 2 parameters.

 

[Glama]

Glama, you need to get a book on learning Objective-C and another one on learning iPhone development. You will learn more quickly that way.

I have one, but it focuses on bigger concepts like inheritance, etc. I havent found a good source of info on the actually syntax and "grammar" of objective-C.

 

[Glama]

Thanks FarSeide and lloyddean. Obj-c is tough to get used after years of

integer mymethod(param1, param2)

 

[PhoneyDeveloper]

What books do you have?

Have you read the sticky: iPhone Developer FAQ?

This is almost the same as Objective-C:

integer mymethod(type param1, type param2)

and 

- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section

integer == NSInteger

mymethod == tableView:numberOfRowsInSection:

type param1 = UITableView*

type param2 = NSInteger

param1 = tableView

param2 = section

 

[lloyddean]

Thanks FarSeide and lloyddean. Obj-c is tough to get used after years of

integer mymethod(param1, param2)

While I haven't read it this document http://ktd.club.fr/programmation/fichiers/cpp-objc-en.pdf
looks like it might prove helpful to C/C++ programmers coming to Objective-C.

 

[Glama]

While I haven't read it this document http://ktd.club.fr/programmation/fichiers/cpp-objc-en.pdf
looks like it might prove helpful to C/C++ programmers coming to Objective-C.

Thanks lloyddean, it looks promising.