Instruments in Xcode 8.3.2

Purpose

Every iOS developer inevitably runs into two common issues during development:

• Things begin slowing down, bringing with it noticeable stuttering and delays.
• Chrashes emerge from ballooning memory usage.

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If you're new to the iOS landscape I encourage you to experiment with instruments.
In this post I am going to cover 3 instruments I routinely use with every app I lay my hands on.

• You'll learn how to use the Time Profiler to measure the time it takes to execute code.
• You'll see how quickly memory can add up, potentially crashing your app, by using the Allocation instrument.
• You'll discover the ARC (automatic reference counting) isn't so automatic when we dive into the Leaks instrument.

The Example App

swift demo: https://github.com/mcgraw/dojo-instruments

Open Instuments

Step By Step

• Xcode ==> Product ==> Profile
• Choose Time Profiler (Try another is OK)
• navigation top right corner click the + icon, add more Profile (Such as Leaks)
  Image Show

Instrument-1.png

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Instrument-2.png

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Instrument-3.png

Time Profiler

**The Time Profile instrument captures stack trace information depending on interval (default is 1ms).
It provide a decent approximation for how much time a given method took by comparing the state of the stack trace against the interval. **
Step By Step

• Choose Time Profiler View ==> Select the problem area ==> change the config
• Double click the Stack Trace (or Symbol Name) ==> Code View
  Image Show

Timer-1.png

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Timer-2.png

Allocation Profiler

Often times, especially with photo apps, you'll run into scenarios where you must download a lot of images from a server.
If you're not careful memory usage can ballon dramatically.
You must make sure that you are caching images to the side that you expect to reuse.
Step By Step

• Choose Allocation Profiler View ==> Select the problem area ==> change the config
• click the Stack Trace (or Symbol Name) ==> detail Stack Trace
• Double click the detail Stack Trace (or Symbol Name) ==> Code View
  Image Show

Allocation-1.png

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Allocation-2.png

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Allocation-3.png

Leaking Memory

Even though Apple introduced ARC, you need to be aware that the potentail for leaks for leaks do remain. Even if you're using swift.
Step By Step

• Choose Leak Profiler View ==> Select the problem area ==> change the config
• Double click the Stack Trace (or Symbol Name) ==> Code View
  Image Show

Leak-1.png

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Leak-2.png

Reference

• How To Use The 3 Instruments You Should Be Using
• 10 Actionable Performance Tips To Speed Up Your Table View