When to use NSInteger vs int

Question

When should I be using NSInteger vs  int when developing for iOS   I see in the Apple sample code they use NSInteger  or NSUInteger  when passing a value as an argument to a function or returning a value from a function   -  NSInteger someFunc     -  void someFuncWithInt  NSInteger value       But within a function they re just using int to track a value  for  int i  i  lt  something  i         int something  something    somethingElseThatsAnInt        I ve read  been told  that NSInteger is a safe way to reference an integer in either a 64-bit or 32-bit environment so why use int at all

User · Answer

OS X is  LP64    This means that    int is always 32-bits   long long is always 64-bits    NSInteger and long are always pointer-sized   That means they re 32-bits on 32-bit systems  and 64 bits on 64-bit systems   The reason NSInteger exists is because many legacy APIs incorrectly used int instead of long to hold pointer-sized variables  which meant that the APIs had to change from int to long in their 64-bit versions   In other words  an API would have different function signatures depending on whether you re compiling for 32-bit or 64-bit architectures   NSInteger intends to mask this problem with these legacy APIs   In your new code  use int if you need a 32-bit variable  long long if you need a 64-bit integer  and long or NSInteger if you need a pointer-sized variable

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You should use NSIntegers if you need to compare them against constant values such as NSNotFound or NSIntegerMax  as these values will differ on 32-bit and 64-bit systems  so index values  counts and the like  use NSInteger or NSUInteger   It doesn t hurt to use NSInteger in most circumstances  excepting that it takes up twice as much memory  The memory impact is very small  but if you have a huge amount of numbers floating around at any one time  it might make a difference to use ints   If you DO use NSInteger or NSUInteger  you will want to cast them into long integers or unsigned long integers when using format strings  as new Xcode feature returns a warning if you try and log out an NSInteger as if it had a known length  You should similarly be careful when sending them to variables or arguments that are typed as ints  since you may lose some precision in the process   On the whole  if you re not expecting to have hundreds of thousands of them in memory at once  it s easier to use NSInteger than constantly worry about the difference between the two

User · Answer

int   4 byte  fixed irrespective size of the architect  NSInteger   depend upon size of the architect e g  for 4 byte architect   4 byte NSInteger size

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As of currently  September 2014  I would recommend using NSInteger CGFloat when interacting with iOS API s etc if you are also building your app for arm64  This is because you will likely get unexpected results when you use the float  long and int types   EXAMPLE  FLOAT DOUBLE vs CGFLOAT  As an example we take the UITableView delegate method tableView heightForRowAtIndexPath    In a 32-bit only application it will work fine if it is written like this   - float tableView  UITableView   tableView heightForRowAtIndexPath  NSIndexPath   indexPath       return 44      float is a 32-bit value and the 44 you are returning is a 32-bit value  However  if we compile run this same piece of code in a 64-bit arm64 architecture the 44 will be a 64-bit value  Returning a 64-bit value when a 32-bit value is expected will give an unexpected row height   You can solve this issue by using the CGFloat type  - CGFloat tableView  UITableView   tableView heightForRowAtIndexPath  NSIndexPath   indexPath       return 44      This type represents a 32-bit float in a 32-bit environment and a 64-bit double in a 64-bit environment  Therefore when using this type the method will always receive the expected type regardless of compile runtime environment   The same is true for methods that expect integers  Such methods will expect a 32-bit int value in a 32-bit environment and a 64-bit long in a 64-bit environment  You can solve this case by using the type NSInteger which serves as an int or a long based on the compile runtime environemnt

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You usually want to use NSInteger when you don t know what kind of processor architecture your code might run on  so you may for some reason want the largest possible integer type  which on 32 bit systems is just an int  while on a 64-bit system it s a long    I d stick with using NSInteger instead of int long unless you specifically require them   NSInteger NSUInteger are defined as  dynamic typedef s to one of these types  and they are defined like this    if   LP64      TARGET OS EMBEDDED    TARGET OS IPHONE    TARGET OS WIN32    NS BUILD 32 LIKE 64 typedef long NSInteger  typedef unsigned long NSUInteger   else typedef int NSInteger  typedef unsigned int NSUInteger   endif   With regard to the correct format specifier you should use for each of these types  see the String Programming Guide s section on Platform Dependencies

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If you dig into NSInteger s implementation    if   LP64   typedef long NSInteger   else typedef int NSInteger   endif   Simply  the NSInteger typedef does a step for you  if the architecture is 32-bit  it uses int  if it is 64-bit  it uses long  Using NSInteger  you don t need to worry about the architecture that the program is running on

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Why use int at all   Apple uses int because for a loop control variable  which is only used to control the loop iterations  int datatype is fine  both in datatype size and in the values it can hold for your loop  No need for platform dependent datatype here  For a loop control variable even a 16-bit int will do most of the time   Apple uses NSInteger for a function return value or for a function argument because in this case datatype  size  matters  because what you are doing with a function is communicating passing data with other programs or with other pieces of code  see the answer to When should I be using NSInteger vs int  in your question itself        they  Apple  use NSInteger  or NSUInteger  when passing a value as an   argument to a function or returning a value from a function

User · Answer

On iOS  it currently does not matter if you use int or NSInteger  It will matter more if when iOS moves to 64-bits   Simply put  NSIntegers are ints in 32-bit code  and thus 32-bit long  and longs on 64-bit code  longs in 64-bit code are 64-bit wide  but 32-bit in 32-bit code   The most likely reason for using NSInteger instead of long is to not break existing 32-bit code  which uses ints    CGFloat has the same issue  on 32-bit  at least on OS X   it s float  on 64-bit  it s double   Update  With the introduction of the iPhone 5s  iPad Air  iPad Mini with Retina  and iOS 7  you can now build 64-bit code on iOS   Update 2  Also  using NSIntegers helps with Swift code interoperability

[ios] When to use NSInteger vs. int

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