Idiomatic NSArray iteration

src/appkit/app/delegate.rs

@@ -187,13 +187,12 @@ extern "C" fn accepted_cloudkit_share<T: AppDelegate>(this: &Object, _: Sel, _:
 /// Fires when the application receives an `application:openURLs` message.
 extern "C" fn open_urls<T: AppDelegate>(this: &Object, _: Sel, _: id, file_urls: id) {
     let urls = NSArray::retain(file_urls)
-        .map(|url| {
+        .iter()
+        .filter_map(|url| {
             let uri = NSString::retain(unsafe { msg_send![url, absoluteString] });
 
-            Url::parse(uri.to_str())
+            Url::parse(uri.to_str()).ok()
         })
-        .into_iter()
-        .filter_map(|url| url.ok())
         .collect();
 
     app::<T>(this).open_urls(urls);
@@ -263,7 +262,10 @@ extern "C" fn print_files<T: AppDelegate>(
     settings: id,
     show_print_panels: BOOL
 ) -> NSUInteger {
-    let files = NSArray::retain(files).map(|file| NSString::retain(file).to_str().to_string());
+    let files = NSArray::retain(files)
+        .iter()
+        .map(|file| NSString::retain(file).to_str().to_string())
+        .collect();
 
     let settings = PrintSettings::with_inner(settings);
 

src/foundation/array.rs

@@ -41,21 +41,41 @@ impl NSArray {
         unsafe { msg_send![&*self.0, count] }
     }
 
-    /// A helper method for mapping over the backing `NSArray` items and producing a Rust `Vec<T>`.
-    /// Often times we need to map in this framework to convert between Rust types, so isolating
-    /// this out makes life much easier.
-    pub fn map<T, F: Fn(id) -> T>(&self, transform: F) -> Vec<T> {
-        let count = self.count();
-        let objc = &*self.0;
+    /// Returns an iterator over the `NSArray`
+    pub fn iter<'a>(&'a self) -> NSArrayIterator<'a> {
+        NSArrayIterator {
+            next_index: 0,
+            count: self.count(),
+            array: self
+        }
+    }
+}
 
+#[derive(Debug)]
+pub struct NSArrayIterator<'a> {
+    next_index: usize,
+    count: usize,
+
+    array: &'a NSArray
+}
+
+impl Iterator for NSArrayIterator<'_> {
+    type Item = id;
+
+    fn next(&mut self) -> Option<Self::Item> {
         // I don't know if it's worth trying to get in with NSFastEnumeration here. I'm content to
         // just rely on Rust, but someone is free to profile it if they want.
-        (0..count)
-            .map(|index| {
-                let item: id = unsafe { msg_send![objc, objectAtIndex: index] };
-                transform(item)
-            })
-            .collect()
+        if self.next_index < self.count {
+            let objc = &*self.array.0;
+            let index = self.next_index;
+
+            let item: id = unsafe { msg_send![objc, objectAtIndex: index] };
+
+            self.next_index += 1;
+            Some(item)
+        } else {
+            None
+        }
     }
 }
 

src/pasteboard/mod.rs

@@ -106,7 +106,7 @@ impl Pasteboard {
                 }));
             }
 
-            let urls = NSArray::retain(contents).map(|url| NSURL::retain(url)).into_iter().collect();
+            let urls = NSArray::retain(contents).iter().map(|url| NSURL::retain(url)).collect();
 
             Ok(urls)
         }