swift - Cannot invoke '_' with an argument list of type '_' - Which of the two choices should I use? -

i have error. think have 2 choices. 1 best code? differences mean?

cannot invoke 'rgbtohsv' argument list of type '(float,float,float)'

rgbtohsv(cgfloat(r), cgfloat(g), cgfloat(b))

rgbtohsv(cgfloat(), cgfloat(), cgfloat())

also if take @ screen shot if give me pointers regarding other couple of errors great too. know have match types don't know syntax order. http://i.imgur.com/sackg6h.png

thanks

func rgbtohsv(r : cgfloat, g : cgfloat, b : cgfloat) -> (h : cgfloat, s : cgfloat, v : cgfloat) {         var h : cgfloat = 0.0         var s : cgfloat = 0.0         var v : cgfloat = 0.0         let col = uicolor(red: r, green: g, blue: b, alpha: 1.0)         col.gethue(&h, saturation: &s, brightness: &v, alpha: nil)         return (h, s, v)     }    // process frame of video     func captureoutput(captureoutput:avcaptureoutput, didoutputsamplebuffer samplebuffer:cmsamplebuffer, fromconnection connection:avcaptureconnection) {         // if we're paused don't         if currentstate == currentstate.statepaused {             // reset our frame counter             self.validframecounter = 0             return         }      // image buffer     var cvimgref:cvimagebufferref = cmsamplebuffergetimagebuffer(samplebuffer)     // lock image buffer     cvpixelbufferlockbaseaddress(cvimgref, 0)     // access data     var width: size_t = cvpixelbuffergetwidth(cvimgref)     var height:size_t = cvpixelbuffergetheight(cvimgref)     // raw image bytes     let buf = unsafemutablepointer<uint8>(cvpixelbuffergetbaseaddress(cvimgref))     var bprow: size_t = cvpixelbuffergetbytesperrow(cvimgref)           var r:float = 0.0         var g:float = 0.0         var b:float = 0.0          var y = 0; y < height; y++ {             var x:uint8 = 0; x < width * 4; x += 4 {  // error: '<' cannot applied operands of type 'uint8' , 'int'                 b += buf[x]                 g += buf[x + 1]                 r += buf[x + 2]             }             buf += bprow(unsafemutablepointer(uint8))  // error: '+=' cannot applied operands of type 'unsafemutablepointer<uint8>' , 'size_t'         }         r /= 255 * (width*height)         g /= 255 * (width*height)         b /= 255 * (width*height)       //}         // convert rgb hsv colourspace         var h:float = 0.0         var s:float = 0.0         var v:float = 0.0      rgbtohsv(r, g, b)  // error 

you have lot of type mismatch error.

the type of x should not uint8 because x increase until value of width.

for var x:uint8 = 0; x < width * 4; x += 4 {  // error: '<' cannot applied operands of type 'uint8' , 'int' 

so fix below:

for var x = 0; x < width * 4; x += 4 { 

to increment pointer address, can use advancedby() function.

buf += bprow(unsafemutablepointer(uint8))  // error: '+=' cannot applied operands of type 'unsafemutablepointer<uint8>' , 'size_t' 

like below:

var pixel = buf.advancedby(y * bprow) 

and line,

rgbtohsv(r, g, b)  // error 

there no implicit casts in swift between cgfloat , float unfortunately. should cast explicitly cgfloat.

rgbtohsv(cgfloat(r), g: cgfloat(g), b: cgfloat(b)) 

the whole edited code here:

func rgbtohsv(r: cgfloat, g: cgfloat, b: cgfloat) -> (h: cgfloat, s: cgfloat, v: cgfloat) {     var h: cgfloat = 0.0     var s: cgfloat = 0.0     var v: cgfloat = 0.0     let col = uicolor(red: r, green: g, blue: b, alpha: 1.0)     col.gethue(&h, saturation: &s, brightness: &v, alpha: nil)     return (h, s, v) }  // process frame of video func captureoutput(captureoutput:avcaptureoutput, didoutputsamplebuffer samplebuffer:cmsamplebuffer, fromconnection connection:avcaptureconnection) {     // if we're paused don't     if currentstate == currentstate.statepaused {         // reset our frame counter         self.validframecounter = 0         return     }      // image buffer     var cvimgref = cmsamplebuffergetimagebuffer(samplebuffer)     // lock image buffer     cvpixelbufferlockbaseaddress(cvimgref, 0)     // access data     var width = cvpixelbuffergetwidth(cvimgref)     var height = cvpixelbuffergetheight(cvimgref)     // raw image bytes     let buf = unsafemutablepointer<uint8>(cvpixelbuffergetbaseaddress(cvimgref))     var bprow = cvpixelbuffergetbytesperrow(cvimgref)      var r: float = 0.0     var g: float = 0.0     var b: float = 0.0      var y = 0; y < height; y++ {         var pixel = buf.advancedby(y * bprow)         var x = 0; x < width * 4; x += 4 {  // error: '<' cannot applied operands of type 'uint8' , 'int'             b += float(pixel[x])             g += float(pixel[x + 1])             r += float(pixel[x + 2])         }     }     r /= 255 * float(width * height)     g /= 255 * float(width * height)     b /= 255 * float(width * height)      //}      // convert rgb hsv colourspace     var h: float = 0.0     var s: float = 0.0     var v: float = 0.0      rgbtohsv(cgfloat(r), g: cgfloat(g), b: cgfloat(b))  // error }