Is It Possible to NSLog C Structs (Like CGRect or CGPoint)?

Question

I want to be able to debug C structures without having to explicitly type every property that they consist of.

i.e. I want to be able to do something like this:

CGPoint cgPoint = CGPointMake(0,0);
NSLog(@"%@",cgPoint);

Obviously the '%@' won't work, hence the question.

Tropaeolin

NSLog(@"%@", CGRectCreateDictionaryRepresentation(rect)); – Linis

Try LOG_EXPR from the VTPG_Common library: vgable.com/blog/tag/log_expr – Critter

Answer 1

You can try this:

NSLog(@"%@", NSStringFromCGPoint(cgPoint));

There are a number of functions provided by UIKit that convert the various CG structs into NSStrings. The reason it doesn't work is because %@ signifies an object. A CGPoint is a C struct (and so are CGRects and CGSizes).

Brunhilde

With AppKit on OS X you would need to convert to an NSPoint and then call NSStringFromPoint. For example: NSStringFromPoint(NSPointFromCGPoint(point)) – Brunhilde

NSLog(@"%@", CGRectCreateDictionaryRepresentation(rect)); – Linis

Similar to UI, MK, CL prefixes which while all have meanings to it and need to import a respective .h file like :UIKit, MapKit, CoreLocation; Does the CG prefix mean I should import anything? If not is is just a naming convention?! – Manpower

Answer 2

There are a few functions like:

NSStringFromCGPoint  
NSStringFromCGSize  
NSStringFromCGRect  
NSStringFromCGAffineTransform  
NSStringFromUIEdgeInsets

An example:

NSLog(@"rect1: %@", NSStringFromCGRect(rect1));

Gelsemium

These are the: "single thing in all of iOS development that is most useful but least known" !! Heh – Burford

Note: for Cocoa (OS X) development, these functions don't have "CG" in the name. – Lamdin

Answer 3

NSLog(@"%@", CGRectCreateDictionaryRepresentation(rect));

Linis

Answer 4

I use the following macro to help me out with NSRect:

#define LogRect(RECT) NSLog(@"%s: (%0.0f, %0.0f) %0.0f x %0.0f",
    #RECT, RECT.origin.x, RECT.origin.y, RECT.size.width, RECT.size.height)

You could do something similar for CGPoint:

@define LogCGPoint(POINT) NSLog(@"%s: (%0.0f, %0.0f)",
    #POINT POINT.x, POINT.y);

Using it as follows:

LogCGPoint(cgPoint);

Would produce the following:

cgPoint: (100, 200)

Richers

Why not just use the built in UIKit String Conversion Functions? – Revenuer

I do now. Those are exatly the functions that Alex and steve posted in their answers. – Richers

Would it be worth editing the answer and adding a note at the top "For historic interest only...". I always do that, for example https://mcmap.net/q/87282/-iphone-app-in-landscape-mode-2008-systems/… #5492979 #4213128 ("It's worth noting that this post from the previous decade, is really now only of historic interest.") etc – Burford

This answer is still useful, despite the existence of UIKit conversion functions, because there other structs in other frameworks, which do not have NSStringFrom helpers (eg. MKCoordinateRegion). – Adorl

Answer 5

You can use NSValue for this. An NSValue object is a simple container for a single C or Objective-C data item. It can hold any of the scalar types such as int, float, and char, as well as pointers, structures, and object ids.

Example:

  CGPoint cgPoint = CGPointMake(10,30);
    NSLog(@"%@",[NSValue valueWithCGPoint:cgPoint]);

OUTPUT : NSPoint: {10, 30}

Hope it helps you.

Minervamines

Answer 6

Yes, you can use bellow few functions like: First you have to convert CGPoint struct into string, see example

1) NSStringFromCGPoint,  
2) NSStringFromCGSize,  
3) NSStringFromCGRect,  
4) NSStringFromCGAffineTransform,  
5) NSStringFromUIEdgeInsets,

For example:

1) NSLog(@"NSStringFromCGPoint = %@", NSStringFromCGRect(cgPointValue));

Like this...

Copalm

Answer 7

Since Stack Overflow’s broken RSS just resurrected this question for me, here’s my almost-general solution: JAValueToString

This lets you write JA_DUMP(cgPoint) and get cgPoint = {0, 0} logged.

Puncheon

I did that and I got compile error. Sometimes address of property expression required or something – Offbeat

@Jim Thio: the macro is set up in such a way that the object being inspected must be an lvalue. (I can’t remember why; something about not being able to handle C strings properly otherwise.) In short, assign your property to a temporary variable, then call JA_DUMP on that. – Puncheon

Answer 8

NSLog(@"%@",CGRectCreateDictionaryRepresentation(rect));

Estaestablish

Answer 9

Use Objective-C way to create objects from C primitives

CGRect rect = CGRectMake(1, 2, 3, 4);
CGSize size = CGSizeMake(1, 2);
NSLog(@"%@, %@",@(rect), @(size));

Output: NSRect: {{1, 2}, {3, 4}}, NSSize: {1, 2}

Numerous