thornpig

Relative to margin
@"V:|-[subview]-|"

Relative to border
@"V:|-0-[subview]-0-|"

thornpig

-(BOOL)textView:(UITextView *)textView shouldChangeTextInRange:(NSRange)range replacementText:(NSString *)text
{
  if (text.length == 0 && range.length == 1)
  {
  //backspace is pressed
  }
}

thornpig

-(NSInteger)indexOfTappedCharacterWithTapGesture:(UITapGestureRecognizer *)tapGesture
{
    CGPoint location = [tapGesture locationInView:self];

    // init text storage
    NSTextStorage *textStorage = [[NSTextStorage alloc] initWithAttributedString: self.attributedText];
    NSLayoutManager *layoutManager = [[NSLayoutManager alloc] init];
    [textStorage addLayoutManager:layoutManager];

    // init text container

thornpig

For example, tap gesture is often added to root view to dismiss keyboard on tap on the screen. 
If the root view contains a table view, the tap gesture will block tap on the cell, 
so didselectrowatindexpath will never be called. To let the gesturerecognizer pass touches to the view, add

gestureRecognizer.cancelsTouchesInView = NO; //default value is YES.

thornpig

[UIViewController initWithNibName:] is only used when the view controller is created directly in code instead of in storyboard. 
The nib file with the nib name if actually for the view of the controller (in fact there is no option for view controller when creating new User Interface file in Xcode), 
so unarchiving the nib file will call
[UIView initWithCoder:]  instead of [UIViewController initWithCoder:]. 
The unarchiving will only be triggered when the view property
of the view controller is accessed for the first time, because [UIView initWithCoder:] is called by [UIViewController loadView]. 

On the other hand, when UIViewController is created in storyboard, either automatically by storyboard or manually by calling 
[UIStoryboard instantiateViewControllerWithItentifier:], 
[UIViewController initWithCoder:] will be called to unarchive the view controller object from the storyboard. 

thornpig

[UIView setAnimationsEnabled: NO];
[button setTitle: @"New Title" forState:UIControlStateNormal];
[button layoutIfNeeded]; //why is this needed?
[UIView setAnimationsEnabled: YES];

thornpig

//update footer view's frame
-(void)updateFrame
{
    CGSize newSize = [self systemLayoutSizeFittingSize: CGSizeMake(CGRectGetWidth(self.frame), CGFLOAT_MAX)];
    CGRect newFrame = self.frame;
    newFrame.size = newSize;
    self.frame = newFrame;
}

//when updating footer, need to call tableFooterView's setter in tableView to invoke resetting the tableview's contentView bounds 

thornpig

xib does not automatically unarchive embedded xib. So simply setting a subview's class in IB to another xib's class won't work.
Need to manually load the embedded xib in -initWithCoder:.
Note that the subview object just loaded needs to be manually added to the view hirerachy.

One trick is to have a wrapper view of the subview to be embedded in the prarent xib.
The wrapper view's layout can be easily setup in the parent xib.
Then in the code, simply add the subview object to the wrapper view in -awakeFromNib:
And it's very easy to setup the subview's constraints to take up the wrapper view.

In -initWithCoder: the IBOutlets have not been connected, so any IBOutlet property is nil in -initWithCoder:

thornpig

Suppose we have a presenting vc, vca,  and a presented vc, vcb
If vca presentes vcb with UIModalPresentationFullScreen style, 
vca's view will be moved to
transitionContext's containerView. During the transition animation 
vcb's view is added on top of vca's view to the containerView. After the trainsition completes vca's view
is removed from the containerView, and vca has disappeared. During the dismissing trainsion, vca's view has to be
inserted to the containerView beneath vcb's view, so that vca's view will be revealed
as vcb's view moves off screen. If vca's view is not inserted back to containerView, a
black screen will be displayed at the end of the transition before vca's view appears.

thornpig

ssh to node server
sudo apt-get update
sudo apt-get install git nodejs npm supervisor

ssh to mongodb server
sudo vi /etc/mongod.conf
change binip to 0.0.0.0

on dev terminal
gcloud compute firewall-rules create default-allow-mongo \