To have an IOS app Screen Design we used which of the following tool?

What does the "id" type mean?

How do you concatenate two NSStrings *foo and NSString *bar to form a new NSString *baz?

Which of the following is a Singleton?

What framework does the class UIButton come from?

If you define a new class called Foo which inherits from NSObject, how do you create a new instance of it?

What does ARC stand for?

What's wrong with this code?float x = 5.;

What is foo? -(float)foo;

What is the key difference between NSDictionary and NSMutableDictionary?

Property defaults include _?