From 9c18774c349cbb0821f59f77c6fff3908139bff7 Mon Sep 17 00:00:00 2001
From: hamidra <hamid.alipour@live.com>
Date: Fri, 1 Nov 2019 20:49:53 -0700
Subject: add downcast to the tutorial

---
 swift.html.markdown | 5 +++++
 1 file changed, 5 insertions(+)

(limited to 'swift.html.markdown')

diff --git a/swift.html.markdown b/swift.html.markdown
index 1f9fe897..8582131a 100644
--- a/swift.html.markdown
+++ b/swift.html.markdown
@@ -692,6 +692,11 @@ print(mySquare.sideLength) // 4
 // cast instance
 let aShape = mySquare as Shape
 
+// downcast instance: 
+// Because downcasting can fail, the result can be an optional (as?) or an implicitly unwrpped optional (as!).  
+let anOptionalSquare = aShape as? Square // This will return nil if aShape is not a Square
+let aSquare = aShape as! Square // This will throw a runtime error if aShape is not a Square
+
 // compare instances, not the same as == which compares objects (equal to)
 if mySquare === mySquare {
     print("Yep, it's mySquare")
-- 
cgit v1.2.3


From 88795664c5ff1980f41bfa39f853cef12f60e92e Mon Sep 17 00:00:00 2001
From: Cory Forsyth <cory.forsyth@gmail.com>
Date: Mon, 2 Dec 2019 16:57:13 -0500
Subject: Return value of `findIndex` is `Optional<Int>`

---
 swift.html.markdown | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

(limited to 'swift.html.markdown')

diff --git a/swift.html.markdown b/swift.html.markdown
index 1f9fe897..8c1a7755 100644
--- a/swift.html.markdown
+++ b/swift.html.markdown
@@ -904,7 +904,7 @@ func findIndex<T: Equatable>(array: [T], valueToFind: T) -> Int? {
     }
     return nil
 }
-findIndex(array: [1, 2, 3, 4], valueToFind: 3) // 2
+findIndex(array: [1, 2, 3, 4], valueToFind: 3) // Optional(2)
 
 // You can extend types with generics as well
 extension Array where Array.Element == Int {
-- 
cgit v1.2.3