7. Key-value Programming Approaches | Objective C Memory Management Essentials

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Objective C Memory Management Essentials

By : Tang

3.3 (3)

Objective C Memory Management Essentials

3.3 (3)

By: Tang

Overview of this book

If you are new to Objective-C or a veteran in iOS application development, this is the book for you. This book will ensure that you can actively learn the methods and concepts in relation to memory management in a more engaging way. Basic knowledge of iOS development is required for this book.

Preface

Preface

What this book covers

What you need for this book

Who this book is for

Conventions

Reader feedback

Customer support

Free Chapter

1. Introduction to Objective-C Memory Management

1. Introduction to Objective-C Memory Management

Why do we need memory management in Objective-C?

An object's ownership and life cycle

Ownership of object and reference counting

What's a memory leak and why pay attention to it?

What is an object within Objective-C?

Summary

2. Automatic Reference Counting

2. Automatic Reference Counting

What is ARC and how does it work?

How ARC looks

Project settings for ARC

A memory model in Objective-C

What you need to know about ARC and weak references

Summary

3. Using Autorelease Pools

3. Using Autorelease Pools

Understanding the autorelease pool mechanism

Autorelease pool mechanism

An overview of Apple autoreleased classes

ARC and autorelease

Autorelease pool blocks and threads

Summary

4. Object Creation and Storage

4. Object Creation and Storage

Creation and initialization of objects

What is a class?

Object immutability

Object mutability

Inheritance

Convenience initializers

An Objective-C programmer's responsibility

The singleton pattern

Creating @property

Creating custom methods

String formatting

Summary

5. Managing Your Application Data

5. Managing Your Application Data

Device memory

Caching

SQLite

Summary

6. Using Core Data for Persistence

6. Using Core Data for Persistence

Why use Core Data?

Understanding Core Data concepts

Putting it into practice

Getting into the code

Saving data into the persistent store

Deleting data from the persistent store

Updating data

Summary

7. Key-value Programming Approaches

7. Key-value Programming Approaches

What is key-value coding or KVC?

The NSKeyValueCoding protocol

Manual subsets of NSKeyValueCoding behavior

Associated objects

Selectors as keys

Maximum flexibility and handling unusual keys/values

Key-value observing

Summary

8. Introduction to Swift

8. Introduction to Swift

Welcome to Swift

Basics of Swift

Memory management in Swift

Summary

9. Memory Management and Debugging

9. Memory Management and Debugging

Memory leaks

Using the debugger and breakpoints

Collecting data on your app

Plumbing memory leaks

Using the LLVM / Clang Static Analyzer

Summary

10. Tips and Tricks for Memory Management

10. Tips and Tricks for Memory Management

Objective-C, C, and memory management

Getters and setters

The property attribute in Objective-C

Performance guidelines

Don't overthink about memory management

When to avoid KVC and KVO

Summary

11. Features of Xcode 6

11. Features of Xcode 6

Introducing Xcode 6

What's new in storyboard

Debugging in Xcode 6

What's new in Interface Builder

Playground for Swift

Summary

Index

Index

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Selectors as keys

Normally, KVC looks up for a property key and acts only after the property key is found. The other approach is about acting on an object's property in the lookup process. There is a lookup method in Objective-C core and its keys are used as selectors.

The following line of code is how you implement this lookup method:

objc_msgSend(myObject, mySetterSelector, myValue);

Note

This method is very similar to the manual implementation of the instance variable's setter, but instead of using the key to form a selector to do a look up, it uses the selector itself as the key.

Advantages of using selectors as keys

It's possible to get and set non-object data.
From all approaches that handles methods, this is the fastest one.

Disadvantages of using selectors as keys

You need different selectors for get and set
Since selectors are not objects, it's impossible to store directly in NSArray and NSDictionary. Instead, you can use NSValue or Core Foundation

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