OK, I'm a bit late, but I finally started to look at Swift, after having programmed a lot in Objective-C.
One thing that strikes me, is the
'var' keyword is used to declare a variable and 'let' keyword is used to declare a constant. The value of a constant cannot be changed once it is set, whereas a variable can be set to a different value in the future. These two keywords are important because in Objective-C we have different-different classes for immutable and mutable String (NSString and NSMutableString), immutable and mutable Array(NSArray and NSMutableArray), etc. For e.g.
var str1 = "Mutable" // In Objective-C, we use NSMutableString class for this let str2 = "Immutable" // In Objective-C, we use NSString class for this var arr1 = ["Mutable1", "Mutable2"] // In Objective-C, we use NSMutableAray class for this let arr2 = ["Immutable1","Immutable2"] // In Objective-C, we use NSArray class for this
Hope this will help you.