ios app maximum memory budget

Question

I m working on an ios game that s targeting as a minimum the 3gs  We are using HD assets for retina display devices  iphone 4  ipod touch 4th gen    Memory wise  Ipod Touch 4th gen seems to be the most constraint device for us since it has the same amount of RAM  256 compared to Iphone 4 s 512  as 3gs but we re using HD assets on it  The app used to crash when trying to load 100-110mb of ram but now that we re down to 70MB  we ve never had loading crash   After lots of searching around  there seems to be no official hard limit so how should we go about knowing what memory budget to use to be safe   We want to be able to give the artists a budget they can use without memory worries for each map

User · Answer

I created one more list by sorting Jaspers list by device RAM (I made my own tests with Split's tool and fixed some results - check my comments in Jaspers thread).

device RAM: percent range to crash

256MB: 49% - 51%
512MB: 53% - 63%
1024MB: 57% - 68%
2048MB: 68% - 69%
3072MB: 63% - 66%
4096MB: 77%
6144MB: 81%

Special cases:

iPhone X (3072MB): 50%
iPhone XS/XS Max (4096MB): 55%
iPhone XR (3072MB): 63%
iPhone 11/11 Pro Max (4096MB): 54% - 55%

Device RAM can be read easily:

[NSProcessInfo processInfo].physicalMemory

From my experience it is safe to use 45% for 1GB devices, 50% for 2/3GB devices and 55% for 4GB devices. Percent for macOS can be a bit bigger.

User · Answer

Starting with iOS13  there is an Apple-supported way of querying this by using   include  lt os proc h gt   size t os proc available memory void    Introduced here  https   developer apple com videos play wwdc2019 606   Around min 29-ish   Edit   Adding link to documentation https   developer apple com documentation os 3191911-os proc available memory language objc

User · Answer

I think you ve answered your own question  try not to go beyond the 70 Mb limit  however it really depends on many things  what iOS version you re using  not SDK   how many applications running in background  what exact memory you re using etc   Just avoid the instant memory splashes  e g  you re using 40 Mb of RAM  and then allocating 80 Mb s more for some short computation   In this case iOS would kill your application immediately    You should also consider lazy loading of assets  load them only when you really need and not beforehand

User · Answer

In my app  user experience is better if more memory is used  so I have to decide if I really should free all the memory I can in didReceiveMemoryWarning  Based on Split s and Jasper Pol s answer  using a maximum of 45  of the total device memory appears to be a safe threshold  thanks guys    In case someone wants to look at my actual implementation    import  mach mach h   -  void didReceiveMemoryWarning          Remember to call super      super didReceiveMemoryWarning           If we are using more than 45  of the memory  free even important resources         because the app might be killed by the OS if we don t     if   self   getMemoryUsedPer1   gt  0 45                   Free important resources here               Free regular unimportant resources always here    -  float   getMemoryUsedPer1       struct mach task basic info info      mach msg type number t size   sizeof info       kern return t kerr   task info mach task self    MACH TASK BASIC INFO   task info t  amp info   amp size       if  kerr    KERN SUCCESS                float used bytes   info resident size          float total bytes    NSProcessInfo processInfo  physicalMemory            NSLog   Used   f MB out of  f MB   f      used bytes   1024 0f   1024 0f  total bytes   1024 0f   1024 0f  used bytes   100 0f   total bytes           return used bytes   total bytes            return 1      Swift  based on this answer    func   getMemoryUsedPer1   - gt  Float       let MACH TASK BASIC INFO COUNT    sizeof mach task basic info data t    sizeof natural t       let name   mach task self      let flavor   task flavor t MACH TASK BASIC INFO      var size   mach msg type number t MACH TASK BASIC INFO COUNT      var infoPointer   UnsafeMutablePointer lt mach task basic info gt  alloc 1      let kerr   task info name  flavor  UnsafeMutablePointer infoPointer    amp size      let info   infoPointer move       infoPointer dealloc 1      if kerr    KERN SUCCESS               var used bytes  Float   Float info resident size          var total bytes  Float   Float NSProcessInfo processInfo   physicalMemory          println  Used    used bytes   1024 0   1024 0  MB out of   total bytes   1024 0   1024 0  MB    used bytes   100 0   total bytes               return used bytes   total bytes           return 1

User · Answer

-  float   getMemoryUsedPer1       struct mach task basic info info      mach msg type number t size   MACH TASK BASIC INFO      kern return t kerr   task info mach task self    MACH TASK BASIC INFO   task info t  amp info   amp size       if  kerr    KERN SUCCESS                float used bytes   info resident size          float total bytes    NSProcessInfo processInfo  physicalMemory            NSLog   Used   f MB out of  f MB   f      used bytes   1024 0f   1024 0f  total bytes   1024 0f   1024 0f  used bytes   100 0f   total bytes           return used bytes   total bytes            return 1      If one will use TASK BASIC INFO COUNT instead of MACH TASK BASIC INFO  you will get   kerr    KERN INVALID ARGUMENT  4

User · Answer

By forking SPLITS repo  I built one to test iOS memory that can be allocated to the Today s Extension   iOSMemoryBudgetTestForExtension  Following is the result that i got in iPhone 5s  Memory Warning at 10 MB  App Crashed at 12 MB  By this means Apple is merely allowing any extensions to work with their full potential

User · Answer

You should watch session 147 from the WWDC 2010 Session videos  It is  Advanced Performance Optimization on iPhone OS  part 2   There is a lot of good advice on memory optimizations   Some of the tips are    Use nested NSAutoReleasePools to make sure your memory usage does not spike  Use CGImageSource when creating thumbnails from large images  Respond to low memory warnings

User · Answer

Working with the many answers above  I have implemented Apples new method os proc available memory   for iOS 13  coupled with NSByteCountFormatter which offers a number of useful formatting options for nicer output of the memory    include  lt os proc h gt         -  NSString   memoryStringForBytes  unsigned long long memoryBytes       NSByteCountFormatter  byteFormatter     NSByteCountFormatter alloc  init       byteFormatter allowedUnits   NSByteCountFormatterUseGB      byteFormatter countStyle   NSByteCountFormatterCountStyleMemory      NSString  memoryString    byteFormatter stringFromByteCount memoryBytes       return memoryString     -  void memoryLoggingOutput       if   available iOS 13 0                NSLog   Physical memory available        self memoryStringForBytes  NSProcessInfo processInfo  physicalMemory            NSLog   Memory A  brackets         self memoryStringForBytes  long os proc available memory              NSLog   Memory B  no brackets         self memoryStringForBytes  long os proc available memory              Important note  Do not forget the    at the end  I have included both NSLog options in in the memoryLoggingOutput method because it does not warn you that they are missing and failure to include the brackets returns an unexpected yet constant result   The string returned from the method memoryStringForBytes outputs values like so   NSLog         self memoryStringForBytes  long os proc available memory         1 93 GB    2 seconds later NSLog         self memoryStringForBytes  long os proc available memory         1 84 GB

User · Answer

Results of testing with the utility Split wrote  link is in his answer    device   crash amount total amount percentage of total    iPad1  127MB 256MB 49  iPad2  275MB 512MB 53  iPad3  645MB 1024MB 62  iPad4  585MB 1024MB 57    iOS 8 1  iPad Mini 1st Generation  297MB 512MB 58  iPad Mini retina  696MB 1024MB 68   iOS 7 1  iPad Air  697MB 1024MB 68  iPad Air 2  1383MB 2048MB 68   iOS 10 2 1  iPad Pro 9 7   1395MB 1971MB 71   iOS 10 0 2  14A456   iPad Pro 10 5     3057 4000 76   iOS 11 beta4   iPad Pro 12 9     2015   3058 3999 76   iOS 11 2 1  iPad Pro 12 9     2017   3057 3974 77   iOS 11 beta4  iPad Pro 11 0     2018   2858 3769 76   iOS 12 1  iPad Pro 12 9     2018  1TB   4598 5650 81   iOS 12 1  iPad 10 2  1844 2998 62   iOS 13 2 3  iPod touch 4th gen  130MB 256MB 51   iOS 6 1 1  iPod touch 5th gen  286MB 512MB 56   iOS 7 0  iPhone4  325MB 512MB 63  iPhone4s  286MB 512MB 56  iPhone5  645MB 1024MB 62  iPhone5s  646MB 1024MB 63  iPhone6  645MB 1024MB 62   iOS 8 x  iPhone6   645MB 1024MB 62   iOS 8 x  iPhone6s  1396MB 2048MB 68   iOS 9 2  iPhone6s   1392MB 2048MB 68   iOS 10 2 1  iPhoneSE  1395MB 2048MB 69   iOS 9 3  iPhone7  1395 2048MB 68   iOS 10 2  iPhone7   2040MB 3072MB 66   iOS 10 2 1  iPhone8  1364 1990MB 70   iOS 12 1  iPhone X  1392 2785 50   iOS 11 2 1  iPhone XS  2040 3754 54   iOS 12 1   iPhone XS Max  2039 3735 55   iOS 12 1  iPhone XR  1792 2813 63   iOS 12 1  iPhone 11  2068 3844 54   iOS 13 1 3  iPhone 11 Pro Max  2067 3740 55   iOS 13 2 3

User · Answer

I created small utility which tries to allocate as much memory as possible to crash and it records when memory warnings and crash happened  This helps to find out what s the memory budget for any iOS device   https   github com Split82 iOSMemoryBudgetTest

[iphone] ios app maximum memory budget

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