I am doing a shopping cart tutorial: I have an array that collects input from a text field, and then displays it in the NSTableView. You can check an item, and remove it from the list. I want to display a warning only if something is checked. So, I have this:
-(IBAction)removeItemFromShoppingList:(id)sender {
int selectedItemIndex = [shoppingListTableView selectedRow];
if (selectedItemIndex == -1) return;
NSAlert *alert = [[NSAlert alloc] init];
...
[alert runModal];
[alert release];
}
On line 2 here (int selectedItemIndex...
) I get a yellow warning: Implicit conversion loses integer precision:’NSInteger’ (aka ‘long’) to ‘int’.
Why?
From apple's documentation:
When building 32-bit applications, NSInteger is a 32-bit integer. A 64-bit application treats NSInteger as a 64-bit integer.
#if __LP64__ || TARGET_OS_EMBEDDED || TARGET_OS_IPHONE || TARGET_OS_WIN32 || NS_BUILD_32_LIKE_64
typedef long NSInteger;
#else
typedef int NSInteger;
#endif
UPDATE:
Explain in detail:
[shoppingListTableView selectedRow]
returns a NSInteger, and you are building an 64-bit application, so it is in fact a long
.
You can use long selectedItemIndex
instead of int selectedItemIndex
to suppress this warning, but the warning appears again when building 32-bit version.
A better way is using NSInteger selectedItemIndex
, which handles this case correctly.