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  • Book Overview & Buying Objective C Memory Management Essentials
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Objective C Memory Management Essentials

Objective C Memory Management Essentials

By : Tang
3.3 (3)
Buy this Book
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Objective C Memory Management Essentials

Objective C Memory Management Essentials

3.3 (3)
By: Tang
Buy this Book

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.
Table of Contents (13 chapters)
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Preface
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Preface
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What this book covers
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What you need for this book
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Who this book is for
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Conventions
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Reader feedback
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Customer support
Free Chapter
1
1. Introduction to Objective-C Memory Management
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1. Introduction to Objective-C Memory Management
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Why do we need memory management in Objective-C?
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An object's ownership and life cycle
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Ownership of object and reference counting
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What's a memory leak and why pay attention to it?
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What is an object within Objective-C?
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Summary
2
2. Automatic Reference Counting
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2. Automatic Reference Counting
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What is ARC and how does it work?
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How ARC looks
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Project settings for ARC
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A memory model in Objective-C
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What you need to know about ARC and weak references
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Summary
3
3. Using Autorelease Pools
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3. Using Autorelease Pools
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Understanding the autorelease pool mechanism
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Autorelease pool mechanism
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An overview of Apple autoreleased classes
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ARC and autorelease
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Autorelease pool blocks and threads
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Summary
4
4. Object Creation and Storage
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4. Object Creation and Storage
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Creation and initialization of objects
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What is a class?
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Object immutability
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Object mutability
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Inheritance
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Convenience initializers
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An Objective-C programmer's responsibility
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The singleton pattern
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Creating @property
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Creating custom methods
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String formatting
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Summary
5
5. Managing Your Application Data
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5. Managing Your Application Data
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Device memory
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Caching
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SQLite
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Summary
6
6. Using Core Data for Persistence
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6. Using Core Data for Persistence
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Why use Core Data?
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Understanding Core Data concepts
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Putting it into practice
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Getting into the code
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Saving data into the persistent store
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Deleting data from the persistent store
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Updating data
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Summary
7
7. Key-value Programming Approaches
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7. Key-value Programming Approaches
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What is key-value coding or KVC?
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The NSKeyValueCoding protocol
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Manual subsets of NSKeyValueCoding behavior
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Associated objects
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Selectors as keys
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Maximum flexibility and handling unusual keys/values
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Key-value observing
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Summary
8
8. Introduction to Swift
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8. Introduction to Swift
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Welcome to Swift
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Basics of Swift
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Memory management in Swift
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Summary
9
9. Memory Management and Debugging
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9. Memory Management and Debugging
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Memory leaks
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Using the debugger and breakpoints
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Collecting data on your app
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Plumbing memory leaks
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Using the LLVM / Clang Static Analyzer
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Summary
10
10. Tips and Tricks for Memory Management
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10. Tips and Tricks for Memory Management
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Objective-C, C, and memory management
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Getters and setters
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The property attribute in Objective-C
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Performance guidelines
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Don't overthink about memory management
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When to avoid KVC and KVO
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Summary
11
11. Features of Xcode 6
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11. Features of Xcode 6
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Introducing Xcode 6
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What's new in storyboard
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Debugging in Xcode 6
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What's new in Interface Builder
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Playground for Swift
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Summary
12
Index
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Index

When to avoid KVC and KVO

KVC and KVO, which we covered previously in Chapter 7, Key-value Programming Approaches, seems like a great mechanism for notifications at a very granular level, but it is possible to go wrong with KVO if you use it incorrectly. The removeObserver method will crash if you are not the observer for that key path, so keeping an exact track of the properties that you are observing is a must.

KVO only has one callback method. If you have multiple notifications, you need to handle them within one callback method, which makes your code inelegant and clunky like this:

- (void)observeValueForKeyPath:(NSString *)keyPath ofObject:(id)object change:(NSDictionary *)change context:(void *)context {
  if ([keyPath isEqualToString:@"mySize"])
  {
            //Do something else
      }
   else if ([keyPath isEqualToString:@"anotherSize"])
   {
    //Do something else
  }
}

With a few more notifications, you will write a lot of if-else statements and you will be able to see how unwieldy...

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