How to create a custom(self designed) uialertview in iOS

Question

I stumbled across a lovely ui concept. I am wondering how could we create a "pop up" window like this in iOS(iPhone).

I have 3 questions:

1. How do we achieve that pop up style window?
2. What is the best approach to do that?

Thank you

EDIT: I would like to create a custom control like this.

Answer 1

It seems that the better way is to:

1- Create a class that inherits UIView and has a delegate class too. your .h file should be something like this:

#import <UIKit/UIKit.h>
@class MYPopUpView;

//Your delegate class
@protocol PopUpViewDelegate <NSObject>

- (void) popUpView:(MYPopUpView *)popUpView clickedButtonAtIndex:(NSInteger) index;

@end

//Your view interface
@interface LIPopUpView : UIView{
    NSObject<LIPopUpViewDelegate> *_delegate;
}
//Your methods and properties
@end

2- In the initializer of your .m file implement the UI of your PopUpView

3- For the circle you can use UILayer or even a custom button and when user clicks it fire your delegate methods.

4- Define a show methods with following code for showing the popUp:

- (void) show
{
    UIWindow *window = [UIApplication sharedApplication].windows.lastObject;
    [window addSubview:self];
    [window bringSubviewToFront:self];
}

5- Fire the show method of you popUp object to show the popUp

6- For hiding it, define the close methods like below and fire it from the caller class.

- (void) close
{
    [self removeFromSuperview];
}