Waiting for XCUIElement to exist

XCTestCase+Additions.m

    //Usage example:
    
    //XCUIElement *newFileButton = self.app.windows.buttons[@"New File"];
    //[self waitForElementToExist:newFileButton timeout:20.0];
    //[newFileButton click];

- (void)waitForElementToExist:(XCUIElement *)element timeout:(NSTimeInterval)timeout
{
    NSPredicate *existsPredicate = [NSPredicate predicateWithFormat:@"exists == 1"];
    [self expectationForPredicate:existsPredicate evaluatedWithObject:element handler:nil];
    [self waitForExpectationsWithTimeout:timeout handler:nil];
}