Initialize Array of Objects using NSArray

Question

I m pretty new to Objective-C and iOS so I ve been playing around with the Picker View  I ve defined a Person Class so that when you create a new Person it automatically gives that person a name and age    import  Person h    implementation Person   synthesize personName  age   - id init       self    super init       if self                personName    self randomName           age    self randomAge              return self     - NSString    randomName       NSString  name      NSArray  nameArr    NSArray arrayWithObjects    Jill Valentine     Peter Griffin     Meg Griffin     Jack Lolwut                                 Mike Roflcoptor     Cindy Woods     Jessica Windmill     Alexander The Great                                 Sarah Peterson     Scott Scottland     Geoff Fanta     Amanda Pope     Michael Meyers                                 Richard Biggus     Montey Python     Mike Wut     Fake Person     Chair                               nil       NSUInteger randomIndex   arc4random      nameArr count       name    nameArr objectAtIndex  randomIndex       return name     - NSInteger    randomAge         lowerBound   arc4random      upperBound - lowerBound       NSInteger  num    NSInteger   1   arc4random      99 - 1         return num      end   Now I want to make an array of Persons so I can throw a bunch into the picker  pick one Person and show their age  First though I need to make an array of Persons  How do I make an array of objects  initialize and allocate them

User · Answer

No one commenting on the randomAge method    This is so awfully wrong  it couldn t be any wronger    NSInteger is a primitive type - it is most likely typedef d as int or long   In the randomAge method  you calculate a number from about 1 to 98    Then you can cast that number to an NSNumber  You had to add a cast because the compiler gave you a warning that you didn t understand  That made the warning go away  but left you with an awful bug  That number was forced to be a pointer  so now you have a pointer to an integer somewhere in the first 100 bytes of memory    If you access an NSInteger through the pointer  your program will crash  If you write through the pointer  your program will crash  If you put it into an array or dictionary  your program will crash    Change it either to NSInteger or int  which is probably the best  or to NSNumber if you need an object for some reason  Then create the object by calling  NSNumber numberWithInteger 99  or whatever number you want

User · Answer

There is also a shorthand of doing this   NSArray  persons     person1  person2  person3     It s equivalent to   NSArray  persons    NSArray arrayWithObjects person1  person2  person3  nil     As iiFreeman said  you still need to do proper memory management if you re not using ARC

User · Answer

This way you can Create NSArray  NSMutableArray   NSArray keys   NSArray arrayWithObjects   key1    key2    key3  nil    NSArray objects   NSArray arrayWithObjects   value1    value2    value3  nil

User · Answer

This might not really answer the question  but just in case someone just need to quickly send a string value to a function that require a NSArray parameter   NSArray  data       The String Value      if you need to send more than just 1 string value  you could also use  NSArray  data       The String Value     Second String     Third etc      then you can send it to the function like below  theFunction data

User · Answer

NSMutableArray  persons    NSMutableArray array   for  int i   0  i  lt  myPersonsCount  i          persons addObject   Person alloc  init      NSArray  arrayOfPersons    NSArray arrayWithArray persons      if you want immutable array   also you can reach this without using NSMutableArray   NSArray  persons    NSArray array   for  int i   0  i  lt  myPersonsCount  i         persons    persons arrayByAddingObject   Person alloc  init        One more thing - it s valid for ARC enabled environment  if you going to use it without ARC don t forget to add autoreleased objects into array     persons addObject    Person alloc  init  autorelease

[ios] Initialize Array of Objects using NSArray

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