fix(material/input): resolve memory leak on iOS (#24599)

Author: arturovt

src/material/input/input.ts

@@ -308,24 +308,7 @@ export class MatInput
     // exists on iOS, we only bother to install the listener on iOS.
     if (_platform.IOS) {
       ngZone.runOutsideAngular(() => {
-        _elementRef.nativeElement.addEventListener('keyup', (event: Event) => {
-          const el = event.target as HTMLInputElement;
-
-          // Note: We specifically check for 0, rather than `!el.selectionStart`, because the two
-          // indicate different things. If the value is 0, it means that the caret is at the start
-          // of the input, whereas a value of `null` means that the input doesn't support
-          // manipulating the selection range. Inputs that don't support setting the selection range
-          // will throw an error so we want to avoid calling `setSelectionRange` on them. See:
-          // https://html.spec.whatwg.org/multipage/input.html#do-not-apply
-          if (!el.value && el.selectionStart === 0 && el.selectionEnd === 0) {
-            // Note: Just setting `0, 0` doesn't fix the issue. Setting
-            // `1, 1` fixes it for the first time that you type text and
-            // then hold delete. Toggling to `1, 1` and then back to
-            // `0, 0` seems to completely fix it.
-            el.setSelectionRange(1, 1);
-            el.setSelectionRange(0, 0);
-          }
-        });
+        _elementRef.nativeElement.addEventListener('keyup', this._iOSKeyupListener);
       });
     }
 
@@ -360,6 +343,10 @@ export class MatInput
     if (this._platform.isBrowser) {
       this._autofillMonitor.stopMonitoring(this._elementRef.nativeElement);
     }
+
+    if (this._platform.IOS) {
+      this._elementRef.nativeElement.removeEventListener('keyup', this._iOSKeyupListener);
+    }
   }
 
   ngDoCheck() {
@@ -519,4 +506,23 @@ export class MatInput
     const element = this._elementRef.nativeElement as HTMLSelectElement;
     return this._isNativeSelect && (element.multiple || element.size > 1);
   }
+
+  private _iOSKeyupListener = (event: Event): void => {
+    const el = event.target as HTMLInputElement;
+
+    // Note: We specifically check for 0, rather than `!el.selectionStart`, because the two
+    // indicate different things. If the value is 0, it means that the caret is at the start
+    // of the input, whereas a value of `null` means that the input doesn't support
+    // manipulating the selection range. Inputs that don't support setting the selection range
+    // will throw an error so we want to avoid calling `setSelectionRange` on them. See:
+    // https://html.spec.whatwg.org/multipage/input.html#do-not-apply
+    if (!el.value && el.selectionStart === 0 && el.selectionEnd === 0) {
+      // Note: Just setting `0, 0` doesn't fix the issue. Setting
+      // `1, 1` fixes it for the first time that you type text and
+      // then hold delete. Toggling to `1, 1` and then back to
+      // `0, 0` seems to completely fix it.
+      el.setSelectionRange(1, 1);
+      el.setSelectionRange(0, 0);
+    }
+  };
 }