iOS Auto Layout Demystified

Completed Updated for iOS 7 and Xcode 5 Auto Layout transforms the way you create iOS user interfaces. As flexible as it is powerful, Auto Layout gives you unprecedented control over your iOS user interfaces. But Auto Layout has a reputation for difficulty. In iOS Auto Layout Demystified, Second Edition, world-renowned iOS developer and author Erica Sadun strips away the confusion, helping you gain Auto Layout mastery the easiest way possible: by example. Fully updated for iOS 7 and Xcode 5, this tutorial delivers everything Sadun’s guides are famous for: clear explanations, expert tips, proven best practices--and, above all, plenty of code to learn from and reuse. Step by step, Sadun explains how Auto Layout “thinks,” how it works, where it fits, and why it’s more useful (and simpler) than you ever imagined. She offers practical solutions for a wide variety of real-world iOS development challenges, plus innovative ways to use Auto Layout to build interactive elements, animations, and more. If you’re an experienced iOS developer, this guide will expand your design possibilities, helping you build apps that are superbly usable and intuitive and stand out even in the most crowded marketplace. Coverage includes Mastering Auto Layout’s basic concepts, techniques, and approach Defining unambiguous, satisfiable constraints that express your layout exactly how you intend Overcoming obstacles to constraint-based user interface design in Interface Builder Using visual formatting to express how items are laid out vertically and horizontally Making visual formats more flexible with metrics dictionaries and layout options Debugging constraints and deciphering those bewildering Xcode log messages Using descriptive techniques to uncover and express natural relationships in your design Applying iOS Auto Layout techniques in Mac OS X apps too

Table of Contents:
Preface     xiii Chapter 1: Introducing Auto Layout     1 Origins     1 Saying “Yes” to Auto Layout     2 Geometric Relationships     3 Content-Driven Layout     5 Prioritized Rules     6 Inspection and Modularization     6 Incremental Adoption     6 Constraints     7 Satisfiability     7 Sufficiency     8 Constraint Attributes     11 About Those Missing Views     12 Underconstrained Missing Views     13 Missing Views with Inconsistent Rules     14 Tracking Missing Views     14 Ambiguous Layout     15 Exercising Ambiguity     16 Visualizing Constraints     17 Intrinsic Content Size     18 Compression Resistance and Content Hugging     20 Image Embellishments     22 Alignment Rectangles     22 Visualizing Alignment Rectangles     24 Alignment Insets     24 Declaring Alignment Rectangles     26 Implementing Alignment Rectangles     27 Exercises     29 Conclusions     30 Chapter 2: Constraints     31 Constraint Types     31 Priorities     33 Conflicting Priorities     33 Enumerated Priorities     34 Content Size Constraints     36 Intrinsic Content Size     36 Content Hugging     36 Compression Resistance     38 Setting Content Size Constraints in Code     39 Setting Content Size Constraints in IB     40 Building Layout Constraints     41 The Layout Constraint Class     42 Constraint Math     42 First and Second Items     43 Creating Layout Constraints     44 Building NSLayoutConstraint Instances     45 Unary Constraints     45 Zero-Item Constraints Are Illegal     46 View Items     47 Constraints, Hierarchies, and Bounds Systems     48 Installing Constraints     50 Removing Constraints     52 Comparing Constraints     54 Matching Constraints     55 Laws of Layout Constraints     57 Exercises     59 Conclusions     59 Chapter 3: Interface Builder Layout     61 Designing in IB     61 Disabling Auto Layout     62 Opting Out of Auto Layout in Code     63 Combining Autosizing with Auto Layout     64 Basic Layout and Auto-Generated Constraints     64 Inferred Constraints     64 Ambiguity Resolution Constraints     67 Size Constraints     69 A Guided Tour of IB Elements     69 Constraint Listings     76 Xcode Labels     78 Adding Xcode Identities     79 Adding Constraints     80 Dragging     81 Pinning and Aligning     83 Previewing Layouts     85 Inspecting Constraints     88 View Size Inspector     90 Frame and Layout Rectangles     91 Other Size Inspector Items     92 The Resolution Menu     92 Updating Frames and Constraints     92 Adding and Resetting Constraints     93 Clearing Constraints     93 Constraints/Resizing Pop-Up Menu     93 Descendants     94 Siblings and Ancestors     95 The Missing Views Problem     95 Balancing Requests     97 Hybrid Layout     100 Building a Nib File for Testing     100 Adding the Nib File in Code     101 Advantages of Hybrid Layout     102 Removing IB-Generated Constraints     104 Exercises     105 Conclusions     108 Chapter 4: Visual Formats     109 Introducing Visual Format Constraints     109 Options     111 Alignment     112 Skipping Options     113 Variable Bindings     113 The Problem with Indirection     113 Indirection Workaround     114 Metrics     115 Real-World Metrics     115 Format String Structure     116 Orientation     116 Retrieving Constraints by Axis     117 View Names     117 Superviews     118 Connections     118 Empty Connections     118 Standard Spacers     119 Numeric Spacers     120 Referencing the Superview     120 Spacing from the Superview     122 Flexible Spaces     122 Parentheses     123 Negative Numbers     124 Priorities     124 Multiple Views     125 View Sizes     126 Format String Components     128 Getting It Wrong     130 NSLog and Visual Formats     131 Constraining to a Superview     132 View Stretching     133 Constraining Size     134 Building Rows or Columns     135 Matching Sizes     136 Why You Cannot Distribute Views     137 How to Pseudo-Distribute Views (Part 1: Equal Centers)      138 Pseudo-Distributing Views (Part 2: Spacer Views)      140 Exercises     143 Conclusions     143 Chapter 5: Debugging Constraints     145 Xcode Feedback     145 Development Feedback     145 Compiler Feedback     146 Runtime     146 Reading Console Logs     147 Autosizing Issues Example     147 Solution: Switch Off Autosizing Translation     148 Auto Layout Conflicts Example     149 Solution: Adjusting Priorities     150 The Nuclear Approach     150 The Balance Approach     151 Tracing Ambiguity     151 Examining Constraint Logs     152 Alignment Constraint Example     152 Standard Spacers Example     153 Equation-Based Constraint Example     153 Complex Equation Example     154 Multiplier and Constant Example     155 A Note About Layout Math     155 Constraint Equation Strings     156 Adding Names     159 Using Nametags     160 Naming Views     161 Describing Views     161 Unexpected Padding Example     164 The Hugged Image Example     165 View Centering Example     166 Retrieving Referencing Constraints     167 Descent Reports     169 Ambiguity Example     170 Expanding on Console Dumps Example     172 Visualizing Constraints     173 Automating Visualization     174 Launch Arguments     175 Internationalization     177 Doubled Strings (iOS/OS X)      177 Flipped Interfaces (OS X)      178 Flipped Interfaces (iOS)      179 Profiling Cocoa Layout     181 Auto Layout Rules of Debugging     183 Exercises     183 Conclusions     184 Chapter 6: Building with Auto Layout     185 Basic Principles of Auto Layout     185 Layout Libraries     186 Building Libraries     187 Planning Interfaces     190 Building for Modularity     191 Updating Constraints     194 Calling Updates and Animating Changes     195 Animating Constraint Changes on OS X     196 Fading Changes     197 Designing for Edge Conditions     198 Building a View Drawer     200 Building the Drawer Layout     203 Managing Layout for Dragged Views     206 Dragged Views     207 Window Boundaries     208 Exercises     211 Conclusions     211 Chapter 7: Layout Solutions     213 Table Cells     213 Auto Layout and Multiple-Height Table Cells     216 Preserving Image Aspect     217 Accordion Sizing     220 Scroll Views     221 Scroll Views and Pure Auto Layout     222 Hybrid Solution     222 Building a Paged Image Scroll View     223 Centering View Groups     226 Custom Multipliers and Random Positions     228 Building Grids     231 Making Room for the Keyboard     233 Inserting Views at Runtime     236 Adding iOS Frame and Constraint Overlays     237 Motion Effects, Dynamic Text, and Containers     238 Exercises     238 Conclusions     238 Appendix A: Answers to Exercises     241 Chapter 1     241 Chapter 2     242 Chapter 3     243 Chapter 4     245 Chapter 5     247 Chapter 6     248 Chapter 7     249 Index     251