Objective-C Fundamentals

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Core Data resources 233 careful to note that you should not override the core behavior methods. Following are the methods of NSManagedObject that should not be overridden: - (id)primitiveValueForKey:(NSString *)key - (void)setPrimitiveValue:(id)value forKey:(NSString *)key - (BOOL)isEqual:(id)anObject - (NSUInteger)hash - (Class)superclass - (Class)class - (id)self - (NSZone *)zone - (BOOL)isProxy - (BOOL)isKindOfClass:(Class)aClass - (BOOL)isMemberOfClass:(Class)aClass - (BOOL)conformsToProtocol:(Protocol *)aProtocol - (BOOL)respondsToSelector:(SEL)aSelector - (id)retain - (oneway void)release - (id)autorelease - (NSUInteger)retainCount - (NSManagedObjectContext *)managedObjectContext - (NSEntityDescription *)entity - (NSManagedObjectID *)objected - (BOOL)isInserted - (BOOL)isUpdated - (BOOL)isDeleted - (BOOL)isFault In most cases, when using Core Data, you won’t need to subclass or worry about any of these issues. But if you do, make sure to leave these methods unaltered so that Core Data’s functionality isn’t impacted. 12.3.2 Core Data attributes An entity is composed of attributes and relationships. An attribute is a simple type, such as a string or an integer. Table 12.1 lists Core Data’s simple attribute types that transform into the listed Objective-C objects. Table 12.1 Simple and native Core Data object types Simple type Int (16, 32, 64) Decimal Float String BOOL Date Binary Objective-C type NSNumber NSNumber NSNumber NSString NSNumber NSDate NSData
234 CHAPTER 12 Reading and writing application data Many objects can be composed solely of these simple types. Defining them in an entity tells Core Data what the data type of each column for the database table will be. Later you can create usable Objective-C classes out of these entities. Core Data generates the class files that represent these entities and hides all of the nasty work usually required to synthesize a native object in and out of a database table. Besides a type, certain attributes can have other parameters defined. Number values (integers, floats, and so on) can have maximums and minimums defined. Strings can have maximum and minimum lengths specified, along with attached regular expressions. Finally, all attributes, no matter what the type, can be defined as optional or mandatory and be given default values. This is useful for modeling information such as a checkout for a store, because during that process, you don’t want to allow the creation of an “order” object without access to all the information you need. There’s still a problem, however. Most objects require some combination of simple and complex types. To handle this problem, you can define relationships for Core Data entities. 12.3.3 Core Data relationships Relationships are the connections among entities—a class’s complex instance variables. A relationship points to another entity defined in your Xcode data model. When defining a relationship, you must also define the kind of association the object has to the class. It can be a one-to-one or a one-to-many relationship. An element with a one-to-many relationship is represented by a mutable set in the entry. With one-tomany relationships, much like with attribute definitions, you can also assign minimums and maximums for the set composing the relationship. A simple example is a task list that tracks multiple tasks assigned to multiple people. As a companion to your Rental Manager application, to help busy agents manage their schedules and tasks, you’ll build an iPhone application that can do the job, including checking off tasks when they’re completed. Let’s make these objects using Core Data’s tools. 12.4 Building the PocketTasks application You start by creating a new Window-based project that uses Core Data for storage (check the Use Core Data for Storage check box when creating the project). Let’s call it PocketTasks. Xcode automatically creates a PocketTasks.xcdatamodel where you’ll define all of your entities. One quick note about the listings in this chapter: for brevity’s sake, releasing instance variables in the dealloc methods of the different classes you build isn’t always explicitly mentioned. You’ll find them in the downloadable source code for this chapter, though. 12.4.1 Examining the Xcode Core Data template Before we look at the data model file, let’s quickly take a peek at the PocketTasksApp- Delegate.m. Notice the following three methods: - (NSManagedObjectContext *)managedObjectContext - (NSManagedObjectModel *)managedObjectModel - (NSPersistentStoreCoordinator *)persistentStoreCoordinator
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Christopher K. Fairbairn Johannes F
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Objective-C Fundamentals CHRISTOPHE
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PART 1 brief contents GETTING START
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viii CONTENTS 1.5 Compiling the Coi
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x CONTENTS 5.4 Declared properties
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xii CONTENTS PART 3 MAKING MAXIMUM
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preface Having been involved in the
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ACKNOWLEDGMENTS xvii Christopher wo
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ABOUT THIS BOOK xix skills. There
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author online Purchase of Objective
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Part 1 Getting started with Objecti
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4 CHAPTER 1 Building your first iOS
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10 CHAPTER 1 Building your first iO
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Data types, variables, and constant
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30 CHAPTER 2 Data types, variables,
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56 CHAPTER 3 An introduction to obj
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Storing data in collections This ch
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76 CHAPTER 4 Storing data in collec
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Creating classes This chapter cover
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Declaring the interface of a class
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Providing an implementation for a c
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Declared properties 109 - (Property
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Declared properties 111 Let’s bri
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Declared properties 113 Although @s
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Creating and destroying objects 115
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Using the class in the Rental Manag
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Summary 123 a number of rental prop
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Subclassing 125 the only class you
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Adding new instance variables 127 s
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Accessing existing instance variabl
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Overriding methods 131 } return gen
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Overriding methods 133 } "for $%@ p
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Class clusters 135 Figure 6.2 Graph
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Categories 137 This code tells the
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Subclassing in your demo applicatio
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Subclassing in your demo applicatio
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Summary 143 6.8 Summary Object-orie
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Defining a protocol 145 Mastering t
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Implementing a protocol 147 7.2.1 C
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Implementing a protocol 149 Listing
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Important protocols 151 iPhone UIKi
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Important protocols 153 executed. T
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Important protocols 155 Any table v
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Important protocols 157 or in table
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Important protocols 159 For s
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Important protocols 161 Listing 7.1
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Dynamic typing and runtime type inf
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Static vs. dynamic typing 165 If yo
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How messaging works 167 Messages ar
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How messaging works 169 8.3.2 Handl
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Runtime type information 171 The if
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Runtime type information 173 8.4.3
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Practical uses of runtime type intr
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Memory management This chapter cove
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Reference counting 179 Figure 9.1 A
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Reference counting 181 the object i
Page 206 and 207: Reference counting 183 Keep yoursel
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Page 210 and 211: Autorelease pools 187 With knowledg
Page 212 and 213: Autorelease pools 189 i * 1000 + j]
Page 214 and 215: Memory zones 191 Memory zones have
Page 216 and 217: Responding to low-memory warnings 1
Page 222 and 223: Summary 199 addObserver:selector:na
Page 224 and 225: Part 3 Making maximum use of framew
Page 226 and 227: Error and exception handling This c
Page 228 and 229: NSError—handling errors the Cocoa
Page 230 and 231: Creating NSError objects 207 chapte
Page 232 and 233: Creating NSError objects 209 10.2.2
Page 234 and 235: Summary 211 10.3.2 Catching excepti
Page 236 and 237: Making your objects KVC-compliant 2
Page 238 and 239: Making your objects KVC-compliant 2
Page 240 and 241: Handling special cases 217 This que
Page 242 and 243: Filtering and matching with predica
Page 248 and 249: Sample application 225 rentingFor:2
Page 250 and 251: Summary 227 The core of the logic o
Page 252 and 253: Core Data history 229 Structured Qu
Page 254 and 255: Core Data objects 231 In Xcode you
Page 258 and 259: Building the PocketTasks applicatio
Page 274 and 275: Beyond the basics 251 How do you us
Page 276 and 277: Beyond the basics 253 All you do is
Page 278 and 279: Beyond the basics 255 attributeName
Page 280 and 281: Blocks and Grand Central Dispatch T
Page 282 and 283: The syntax of blocks 259 What if yo
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Page 286 and 287: The syntax of blocks 263 } [super d
Page 288 and 289: Performing work asynchronously 265
Page 298 and 299: Summary 275 more to learn about GCD
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Page 302 and 303: Understanding NSLog 279 Figure 14.3
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Bringing memory leaks under control
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Detecting zombies 285 (and the appl
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Summary 287 and its ease of use and
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Preparing your iOS device for devel
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Preparing your iOS device for devel
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appendix B The basics of C Througho
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Variable naming conventions 295 As
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Expressions 297 Table B.3 Relationa
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Expressions 299 B.2.4 Assignment op
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Conditional statements 301 based on
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Conditional statements 303 The gene
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Looping statements 305 Not as strai
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Looping statements 307 One importan
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Looping statements 309 As in a do l
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Summary 311 CONTINUE The continue s
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A short history of Objective-C 313
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The iPhone SDK: Safari 315 C.2 Alte
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The iPhone SDK: Safari 317 C.3.2 ha
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The iPhone SDK: Safari 319 It’s i
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Scripting languages: Lua and Ruby 3
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Mono (.NET) 323 the iOS platform. F
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Summary 325 Xamarin announced a fol
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index Symbols ^ operator 298 - oper
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INDEX 329 application-specific quer
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INDEX 331 collections (continued) e
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INDEX 333 E e character 35 editButt
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INDEX 335 iOS Developer account 9 i
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INDEX 337 mutableCopyWithZone 190 M
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INDEX 339 Organizer window 291 over
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INDEX 341 setFlag 164 setNilValueFo
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INDEX 343 vardic method 75 variable
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Objective-C Fundamentals

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