viewWillLayoutSubviews: and viewDidLayoutSubviews:
viewWillAppear: and viewDidAppear: etc. (both repeatedly)
didReceiveMemoryWarning
awakeFromNib
- (void)awakeFromNib
Sent to all objects that come out of a storyboard (including your Controller)
Happens before outlets are set! (i.e. before the MVC is “loaded”)
After an object receives an awakeFromNib message, it is guaranteed to have all its outlet instance variables set
Anything that would go in your Controller’s init method would have to go in awakeFromNib
- (void)setup{}; //dosomething which can’t wait until viewDidLoad
- (void)awakeFromNib { [self setup]; }
viewDidLoad
Only get called once
After instantiation and outlet-setting, viewDidLoad is called
Before the actual screen shows up
Geometry of your view (its bounds) is not set yet!
A fantistic place for init. Better than your controller init. for your outlet now is set!
@interface ViewController ()
@property (weak, nonatomic) IBOutlet UIButton *outlineButton;
@end
-(void)viewDidLoad
{
// always call super for letting superclass init.
[super viewDidLoad];
// Do any additional setup after loading the view, typically from a nib.
// because we are not textview, we have to convert title to mutablestring
// then set the title
NSMutableAttributedString *title = [[NSMutableAttributedString alloc] initWithString:self.outlineButton.currentTitle];
[title setAttributes:@{ NSStrokeWidthAttributeName : @5,
NSStrokeColorAttributeName : self.outlineButton.tintColor}
range:NSMakeRange(0, title.length)];
[self.outlineButton setAttributedTitle:title forState:UIControlStateNormal];
}
viewWillLayoutSubviews: and viewDidLayoutSubviews:
Called any time a view’s frame changed and its subviews were thus re-layed out. e.g. autorotation
Put Geometry codes here
viewWillAppear: and viewDidAppear: (both repeatedly)
Repeatedly: view will only get “loaded”(viewDidLoad) once, but it might appear and disappear a lot.
- (void)viewWillAppear:(BOOL)animated; a place to do something if things you display are changing while your MVC is off-screen.
- (void)viewWillDisappear:(BOOL)animated a place to put “remember what’s going on” and cleanup code.
- (void)viewWillDisappear:(BOOL)animated
{
[super viewWillDisappear:animated]; // call super in all the viewWill/Did... methods
// let’s be nice to the user and remember the scroll position they were at ...
[self rememberScrollPosition]; // we’ll have to implement this
// do some other clean up now that we’ve been removed from the screen
[self saveDataToPermanentStore]; // maybe do in did instead?
// but be careful not to do anything time-consuming here, or app will be sluggish
// maybe even kick off a thread to do what needs doing here
}
didReceiveMemoryWarning
iOS gets its right to kill your app if you are a memory eater…
