Question

I am trying to make a time based drawing. For example: define a point for later use.

CGPoint testPoint = CGPointMake(2341.2345, 1350046324.1234);

Then testPoint.y becomes 1350046336.00 which is not we put there.
I am using Xcode 4.5.
Any ideas? Thanks.

Answer 1

CGPoint uses float (32bit) datatypes (at least on iOS6).

From the headers:

CGPointMake(CGFloat x, CGFloat y) ...

with

typedef CGFLOAT_TYPE CGFloat;

and

# define CGFLOAT_TYPE float

So this results in my test code:

CGPoint testPoint1 = CGPointMake(2341.2345, 1350046324.1234);
CGPoint testPoint2 = CGPointMake(2341.2345f, 1350046324.1234f);
double d = 1350046324.1234;
float f = 1350046324.1234;

NSLog(@"%f %f %f %f", testPoint1.y, testPoint2.y, d, f);

printing to the log:

1350046336.000000 1350046336.000000 1350046324.123400 1350046336.000000

So you just left the range of numbers where single precision floats are good enough.
Thats all.

BTW.: I did think CGFloat is double before I stumbled upon your question.