What s the difference between using CGFloat and float

Question

I tend to use CGFloat all over the place  but I wonder if I get a senseless  performance hit  with this  CGFloat seems to be something  heavier  than float  right  At which points should I use CGFloat  and what makes really the difference

User · Answer

just mention that - Jan  2020 Xcode 11 3 iOS13  Swift 5  From the CoreGraphics source code  public struct CGFloat           The native type used to store the CGFloat  which is Float on         32-bit architectures and Double on 64-bit architectures      public typealias NativeType   Double

User · Answer

As  weichsel stated  CGFloat is just a typedef for either float or double  You can see for yourself by Command-double-clicking on  CGFloat  in Xcode     it will jump to the CGBase h header where the typedef is defined  The same approach is used for NSInteger and NSUInteger as well   These types were introduced to make it easier to write code that works on both 32-bit and 64-bit without modification  However  if all you need is float precision within your own code  you can still use float if you like      it will reduce your memory footprint somewhat  Same goes for integer values   I suggest you invest the modest time required to make your app 64-bit clean and try running it as such  since most Macs now have 64-bit CPUs and Snow Leopard is fully 64-bit  including the kernel and user applications  Apple s 64-bit Transition Guide for Cocoa is a useful resource

User · Answer

CGFloat is a regular float on 32-bit systems and a double on 64-bit systems  typedef float CGFloat    32-bit typedef double CGFloat    64-bit   So you won t get any performance penalty

User · Answer

Objective-C From the Foundation source code  in CoreGraphics  CGBase h      Definition of  CGFLOAT TYPE    CGFLOAT IS DOUBLE    CGFLOAT MIN   and     CGFLOAT MAX        if defined   LP64     amp  amp    LP64     define CGFLOAT TYPE double   define CGFLOAT IS DOUBLE 1   define CGFLOAT MIN DBL MIN   define CGFLOAT MAX DBL MAX  else   define CGFLOAT TYPE float   define CGFLOAT IS DOUBLE 0   define CGFLOAT MIN FLT MIN   define CGFLOAT MAX FLT MAX  endif     Definition of the  CGFloat  type and  CGFLOAT DEFINED       typedef CGFLOAT TYPE CGFloat   define CGFLOAT DEFINED 1  Copyright  c  2000-2011 Apple Inc  This is essentially doing    if defined   LP64     amp  amp    LP64   typedef double CGFloat   else typedef float CGFloat   endif  Where   LP64   indicates whether the current architecture  is 64-bit  Note that 32-bit systems can still use the 64-bit double  it just takes more processor time  so CoreGraphics does this for optimization purposes  not for compatibility  If you aren t concerned about performance but are concerned about accuracy  simply use double  Swift In Swift  CGFloat is a struct wrapper around either Float on 32-bit architectures or Double on 64-bit ones  You can detect this at run- or compile-time with CGFloat NativeType  and cgFloat native  From the CoreGraphics source code  in CGFloat swift gyb  public struct CGFloat    if arch i386     arch arm        The native type used to store the CGFloat  which is Float on       32-bit architectures and Double on 64-bit architectures    public typealias NativeType   Float  elseif arch x86 64     arch arm64        The native type used to store the CGFloat  which is Float on       32-bit architectures and Double on 64-bit architectures    public typealias NativeType   Double  endif    Specifically  longs and pointers  hence the LP  See also  http   www unix org version2 whatsnew lp64 wp html

User · Answer

As others have said  CGFloat is a float on 32-bit systems and a double on 64-bit systems  However  the decision to do that was inherited from OS X  where it was made based on the performance characteristics of early PowerPC CPUs  In other words  you should not think that float is for 32-bit CPUs and double is for 64-bit CPUs   I believe  Apple s ARM processors were able to process doubles long before they went 64-bit   The main performance hit of using doubles is that they use twice the memory and therefore might be slower if you are doing a lot of floating point operations

[iphone] What's the difference between using CGFloat and float?

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