Auto Layout Demo code

UIButton *button=[UIButton buttonWithType:UIButtonTypeRoundedRect];

    [button setTranslatesAutoresizingMaskIntoConstraints:NO];

    

    [button setTitle:@"action" forState:UIControlStateNormal];

    [self.view addSubview:button];

    

    NSLayoutConstraint *btnCon=[NSLayoutConstraint constraintWithItem:button attribute:NSLayoutAttributeBottom relatedBy:NSLayoutRelationEqual toItem:[button superview] attribute:NSLayoutAttributeBottom multiplier:1.0 constant:-20.0];

    

    NSLayoutConstraint *btnCon2=[NSLayoutConstraint constraintWithItem:button attribute:NSLayoutAttributeCenterX relatedBy:NSLayoutRelationEqual toItem:[button superview] attribute:NSLayoutAttributeCenterX multiplier:1.0 constant:-20.0];

    [self.view addConstraint:btnCon2];

    [self.view addConstraint:btnCon];

Facebook iOS position interview question

   last week Facebook recruit found me in LinkedIn, so he ask me if you would be interested in iOS opportunities within Facebook. I currently live in Shanghai,China, if have a chance go to bay area wok is biggest change in my life.  So I accept his request.
   next is recruiter test question :

 Question 1: When running out of memory, how does the system give your app one last chance to prevent being killed?

a) Autorelease

b) Jetsam

c) Memory Warning

d) UIApplicationWillTerminateNotification



 Question 2: What is the difference between a UIView's 'frame' and its 'bounds'

a) 'frame' defines the view's position and size; 'bounds' defines its clipping rect

b) 'frame' defines the view's clipping rect; 'bounds' defines its position and size

c) 'frame' defines position and size in the coordinate space of its superview; 'bounds' defines position and size in the coordinate space of the view itself

d) They are equal



 Question 3: The delegation pattern is often used to:

a) Report value changes from a Model to a Controller

b) Communicate messages back from one object to its owning object

c) Broadcast messages from a singleton object (e.g. NS User Defaults) to its listener

d) All of the above



Question 4: Which of the following cannot be retained:

a) NSString literal

b) NSNull

c) NSInteger

d) NSNotification

 Question 5: A block cannot:

a) Be subclassed

b) Be retained or released

c) Access 'self' from the scope in which it is declared

d) Be passed as an argument

another question : what does KVO stand for?

   yesterday Facebook Engineer give me a Skype interview:

@interface UIControl: UIView



- (void)addTarget:(id)target action:(SEL)action forControlEvents:(UIControlEvents)controlEvents;




@end




@implementation UIControl




- (void)addTarget:(id)target action:(SEL)action forControlEvents:(UIControlEvents)controlEvents


{


  // How would you implement this?



}



// A UIControlEventTouchUpInside just happened. Let every interested target know…

- (void)_fireTargetsAndActionsForEvent:(UIControlEvents)controlEvent


{


  // ???





}

 





[myButton addTarget:self action:@selector(didTapButton:) forControlEvents:UIControlEventTouchUpInside];

  others question:
how runloop work and autorelease object?
will lead to myButton retain target self?
_fireTargetsAndActionsForEvent complexity?

Today morning, I receive recruiter mail, he told I don't get  chance to next round interview.
I'm very sad, maybe there have many candidates who are best than me.  So I don't have chance work for the company, the interview experience is good for me.