Why did I get the result nil through dataTaskWithURL ?

If you use dataTaskWithURL , your intention might be getting a data from server and display the data to your UI. But, sometimes it makes a problem that the resulted data is nil.

To solve this issue, first of all you must recognize that dataTaskWithURL runs asynchronously. Conversely UI stuffs runs on the main thread on iOS. So the time that you get a data from the server might not be synced with the time you display the data to your UI. So in this case you might see a strange nil value on it.

You can simply think that I can run it sychronously. But, it would cause a bad user experience. So here is a solution which is creating another completionHandler to run it asynchronously. And then if you want to update your UI , remember that the task should be taken on main queue.

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How can I change the modal transition of a presented view controller?

In iOS the default transition between presenting view controller and presented view controller is .CoverVertical. But sometimes you might want to change it to a different animation style.

If you setup a presented view controller , it has a property which calls modalTransitionStyle and you can choose one of styles below,

• CoverVerticial (Default)
• FlipHorizontal
• CrossDissolve
• PartialCurl

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How to point your Godaddy domain to a2Hosting

I recently created an account in a2hosting to host a wordpress website. And then I need to point a domain in Godaddy to a2hosting account.

This video helped me to get it done.

By the way a2hosting’s default option doesn’t provide a public IP address for the account. I use a2hosting’s Shared Hosting Swift product. They charge the additional fee $4 for it.

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The relationship between AnchorPoint and Position in Layer

I felt difficult to understand the relationship between AnchorPoint and Position in Layer. So I found this in stackoverflow. And it helped me a lot to understand it.

Through my testing I got some principle.

• If a layer’s frame is already defined , the anchorpoint doesn’t affect the position of the layer.

• If you change an anchorPoint of a layer which already has a frame and a position , the origin of the layer’s frame will be changed by the setting of anchorPoint.

  let view = UIView(frame: CGRectMake(0,0,400,400))
  view.backgroundColor = UIColor.grayColor()
  let label1 = UILabel(frame: CGRectMake(100,100,100,20))
  label1.text = "Label1"
  print("AnchorPoint: \(label1.layer.anchorPoint) , Frame: \(label1.layer.frame)")
  print("Position: \(label1.layer.position)")
  label1.backgroundColor = UIColor.whiteColor()
  view.addSubview(label1)
  view
  
  // AnchorPoint to (1,1) 
  
  label1.layer.anchorPoint = CGPoint(x: 1.0, y: 1.0)
  label1.text = "Label1"
  print("AnchorPoint: \(label1.layer.anchorPoint) , Frame: \(label1.layer.frame)")
  view.addSubview(label1)
  view
  

• If you set up a layer’s anchorPoint before you set up the frame of the layer, the position of the layer will be affected by setting of the anchorPoint.

  let label2 = UILabel()
  label2.layer.anchorPoint = CGPoint(x: 1.0, y: 1.0)
  label2.frame = CGRect(origin: CGPoint(x: 100,y: 100), size: CGSize(width: 100.0, height: 20.0))
  print("AnchorPoint: \(label2.layer.anchorPoint) , Frame: \(label2.layer.frame)")
  print("Position: \(label2.layer.position)")
  
  let label3 = UILabel()
  label3.layer.anchorPoint = CGPoint(x: 0.0, y: 0.0)
  label3.frame = CGRect(origin: CGPoint(x: 100, y: 100), size: CGSize(width: 100.0, height: 20.0))
  print("AnchorPoint: \(label3.layer.anchorPoint) , Frame: \(label3.layer.frame)")
  print("Position: \(label3.layer.position)")
  

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How can I start UIBezierPath animation from the top of a circle?

When you draw a circle by using core animation , you might use CAShapeLayer and UIBezierPath to draw it.

UIBezierPath(arcCenter: view.center, radius: view.bounds.width / 2, startAngle: startAngle, endAngle: endAngle, clockwise: true).CGPath

The code above there are startAngle and endAngle parameters which affect where your animation start and end. So if you want to draw the circle from a specific position to another position, I recommend this link.

If you want to start from the top of the circle , your startAngle should be M_PI + M_PI_2.

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How to securely use xmlrpc

I like to post an article to wordpress through Byword or Ulysses. And those tools use wordpress’s xmlrpc.php.

By the way if you use xmlrpc.php with your own server , you might face up to infinite attacks which target xmlrpc.php. And I horribly experience it.

If you want to independently operate your wordpress blog on your own server , I recommend to block xmlrpc.php access from anonymous users with the code below.

<FilesMatch "xmlrpc\.php$">
    order deny,allow
    deny from all
    allow from [Your IP address]  // Allow the only your ip address
</FilesMatch>

Put the code above into your .htaccess file in the root folder of wordpress.

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My experience on Upthere

Upthere is a kind of new concept of cloud service such as iCloud, Dropbox, Google Drive. Mostly cloud services save your data in both local and cloud. It could be beneficial for someone who wants to back up their data.

The problem is taking too much storage in your local storage

iPhone 16GB model has been criticized by users because it isn’t enough to fully use. The storage is too small to install bunch of applications from Appstore. Also the size of photos and videos taken by users is getting bigger and bigger.

Upthere provides a solution for it. It doesn’t take much space in your phone or notebook. It just saves thumbnails of photos or videos which are much smaller than fully saving them. So you can save your space with it.

Not enough to replace conventional cloud services

The problem that I faced with Upthere is organizing my documents in it. It suggests Loop as a tool for organizing. But, it isn’t enough to replace the conventional folders. Even they don’t provide tags to organize my files. So I hope that they provide a way for making it better.

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