Exercise 2: Slow Screen, Growing Memory — Possible Solution
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TASK
Say which instruments you would use for each symptom and what you would look
at.

ANSWER
Both start with Product -> Profile so you measure a Release build.

SLOW WHEN OPENED
- Time Profiler.
- Record while opening the screen, then read the call tree. Follow the
  heaviest stack trace, and compare the weight (share of samples) with the
  self column (time in that method itself).

MEMORY HIGHER AFTER TEN OPEN/CLOSE CYCLES
- Allocations first: watch Persistent Bytes, the memory still held. If it
  rises each cycle and does not fall, something is not being released.
- Then Leaks: look for allocations without retainers and check the
  Cycles & Roots view for a retain cycle.

WHY BOTH INSTRUMENTS FOR MEMORY
Leaks may miss a cycle that a live object still references, so Persistent
Bytes in Allocations is a useful second check.