Intermediate iOS Debugging | Ray Wenderlich

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Prepare to learn some new debugging tricks! In this course, you'll improve your skills with LLDB and Xcode.

This is a companion discussion topic for the original entry at https://www.raywenderlich.com/4744-intermediate-ios-debugging
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All videos in the debugging series (Basic and Intermediate iOS Debugging) load very slowly at the time I’m replying (July 25, 2019). This happens only in these series as far as I know. I have hard time learning so far.

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Hi @yossa_bourne,

I’m sorry you’re having trouble with these videos :[

I’m sorry to hear you are having trouble on our site. We’re not able to replicate the issues you are describing so our engineering team recommend trying the following if you haven’t already:

  1. Try a different browser and see if the issue persists.

  2. Is this with all videos or a specific video? I know you said it was two specific courses but if you could try playing some more videos to see if you have the same problem.

  3. Check to see if cookies are causing the problem. You can do this in Chrome by clicking File->new Incognito Window. Then sign in to your raywenderlich.com account and see if the videos will play.

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Please email support@razeware.com if you try the above and are still having trouble. I’m so sorry for the inconvenience here!

Kind regards,
Katie

1 Like
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Hi @katiecollins

Thank you for your response :] I had faced this problem for 2 days (starting on July 24). However, the problem disappeared today and I don’t know why. At least I feel good that I can continue learning right now.

I would like to provide you more information in case you need to inspect further.

  1. Try a different browser and see if the issue persists.
  2. Is this with all videos or a specific video? I know you said it was two specific courses but if you could try playing some more videos to see if you have the same problem.
  1. The problem occurred on Safari and Chrome. I haven’t try other browsers. I use macOS Catalina (beta).
  2. It was all videos in those two courses.

Thank you very much for your help.

Regards,
Yossa

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Hi @yossa_bourne,

I’m glad the problem has resolved itself. Please do let us know if you experience any further issues and apologies for the inconvenience here.

Kind regards,

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Selecting a Debugger

Xcode has two debuggers namely, GDB and LLDB debuggers. GDB is selected by default. LLDB is a debugger that is a part of the LLVM open-source compiler project. You can change the debugger by “edit active schemes” option.

How to Find Coding Errors?

To locate coding-related errors, you need to build your application which will compile the code. In case the code contains errors, the compiler will display all the messages, errors, and warnings with their possible reasons.

You can click Product and then Analyze to locate possible issues in an application.

Set Breakpoints

Breakpoints help us to know the different states of our application objects, which help us identifying many flaws including logical issues. We just need to click over the line number to create a breakpoint. To remove a breakpoint, simply click and drag it out. The following screenshot shows how to set a breakpoint −

When we run the application and select the playVideo button, the application will pause at the line number where we had set the breakpoint. It allows us the time to analyze the state of the application. When the breakpoint is triggered, we will get an output as shown below.

You can easily identify which thread has triggered the breakpoint. In the bottom, you can see objects like self, sender and so on, which hold the values of the corresponding objects and we can expand some of these objects, and see what is the state of each of these objects.

To continue the application we will select the continue button (left most button), in the debug area shown below. The other options include step in, step out and step over.

Exception Breakpoint

We also have exception breakpoints that trigger an application to stop at the location where the exception occurs. We can insert exception breakpoints by selecting the + button after selecting the debug navigator. You will get the following window. Then we need to select Add Exception Breakpoint, which will display the following window.

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Line 125: PhotoFeedModel.swift
api link is broken = https://api.500px.com/v1/photos/search?term=cat&exclude=Nude,People,Fashion&sort=rating&image_size=3&include_store=store_download&include_states=voted&consumer_key=Fi13GVb8g53sGvHICzlram7QkKOlSDmAmp9s9aqC
yields an error

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@jerbeers Can you please help with this when you get a chance? Thank you - much appreciated! :]

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See the discussion here: https://www.raywenderlich.com/4744-intermediate-ios-debugging/lessons/3