Objective C UInt32 Definition - objective-c

Question

i found the following statement in code which I not completely understand:
UInt32 *pixels;
UInt32 *currentPixel = pixels;
UInt32 color = *currentPixel;
The first two lines are clear to me, as these are definitions of UInt32 objects, pixels, and currentPixel.
But the line after does not make sense to me honestly.
Why is it not:
UInt32 *color = currentPixel
but
UInt32 color = *currentPixel
What is the difference in that?
If I remove the * from currentPixel i get the message:
Incompatible pointer to integer conversion initializing 'UInt32' (aka 'unsigned int') with an expression of type 'UInt32 *' (aka 'unsigned int *'); dereference with *
What does dereference with * mean?
Thank you

Answer 1

// alloc height * width * 32 bit memory. pixels is first address.
UInt32 *pixels = (UInt32 *) calloc(height * width, sizeof(UInt32));
// you can do like this
UInt32 color = pixels[3]
// or like this, they are equal.
UInt32 color = *(pixels + 3)
pointer like a array, sometime.
there are a tutorial about pointer:
http://www.cplusplus.com/doc/tutorial/pointers/
UInt32 isn't a object.
it is unsigned long in 32bit machine.
unsigned int in 64bit machine.
there are it's define:
#if __LP64__
typedef unsigned int UInt32;
typedef signed int SInt32;
#else
typedef unsigned long UInt32;
typedef signed long SInt32;
#endif