Question

it’s a hard to explain issue so i hope i can state it

i have a tableview and i want that..

row number 1 have a background and row number 2 have another background .

and row number 3 have a third background..

the fourth row should have the first background and the fifth should have the second ..

and so forth ..

i used this code

if(row+1%1==0){
    bg = [UIImage imageNamed:@"row1.png"];
    selectionBg = [UIImage imageNamed:@"row1.png"];
}

else if(row+1%2==0){
    bg = [UIImage imageNamed:@"row2.png"];
    selectionBg = [UIImage imageNamed:@"row2.png"];
}else if(row+1%3==0){
    bg = [UIImage imageNamed:@"row3.png"];
    selectionBg = [UIImage imageNamed:@"row3.png"];
}

i’m trying to use modulus but i get lost .. so is there a way for that?

thanks in advance

Answer 1

You should use mod 3 because you have three options:

if (row % 3 == 0) {
    // Option A
} else if (row % 3 == 1) {
    // Option B
} else {
    // Option C
}

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By the way, do you understand what a modulo operation does? This might be interesting to read (from Wikipedia):

In computing, the modulo operation finds the remainder of division of
one number by another.

Given two positive numbers, a (the dividend)
and n (the divisor), a modulo n (abbreviated as a mod n) can be
thought of as the remainder, on division of a by n. For instance, the
expression “5 mod 4” would evaluate to 1 because 5 divided by 4 leaves
a remainder of 1, while “9 mod 3” would evaluate to 0 because the
division of 9 by 3 leaves a remainder of 0; there is nothing to
subtract from 9 after multiplying 3 times 3.

---

This is what happens in the code:

row       row % 3   option
0         0         A
1         1         B
2         2         C
3         0         A
4         1         B
5         2         C
6         0         A
…         …         …