macOS objective-c operator ?:

[medasmx]

In an apple developer example(DragNDropOutlineView), the following line of code is present --
"SimpleTreeNode*=(item==nil)?treeData:item;"

I haven't been able to find documentation regarding this online. However, in the Kochan book, a?b:c is called a conditional(if...then, I suppose). It would read if a is true then b otherwise c. From the above statement to me that means, if item==nil then treeData otherwise item. The full block of code is ...

- (NSInteger)outlineView:(NSOutlineView *)outlineView numberOfChildrenOfItem:(id)item {
    SimpleTreeNode *node = (item == nil) ? treeData : item;
    return [node numberOfChildren];

Thanks for any explanation. Adam

 

[SilentPanda]

It's pretty much shorthand for (and this code won't work)..

if (item == nil) {
    node = treeData;
} else {
    node = item;
}

http://en.wikipedia.org/wiki/Ternary_operation

 

[medasmx]

Thanks, Panda. That was fast. Adam