ios - EXC_BAD_INSTRUCTION when trying to pass data to UIViews -

i created call of uiview in draw graph. trying pass new data , have update.

when run app on simulator , click tab in the controller housing view in, receive error:

thread 1: exc_bad_instruction (code=exc_1386_invop, subcode=0x0)

at line:

let maxvalue = graphpoints.maxelement() 

here code view:

@ibdesignable class graphview: uiview {  var graphpoints :[int]!  override init(frame: cgrect) {     super.init(frame: frame) } init(graphpoints: [int]) {     self.graphpoints = graphpoints     super.init(frame: cgrectzero)  }  required init?(coder adecoder: nscoder) {     super.init(coder: adecoder) }  @ibinspectable var startcolor: uicolor = uicolor.redcolor() @ibinspectable var endcolor: uicolor = uicolor.greencolor()  override func drawrect(rect: cgrect) {      let width = rect.width     let height = rect.height      //set background clipping area     let path = uibezierpath(roundedrect: rect,         byroundingcorners: uirectcorner.allcorners,         cornerradii: cgsize(width: 8.0, height: 8.0))     path.addclip()      //2 - current context     let context = uigraphicsgetcurrentcontext()     let colors = [startcolor.cgcolor, endcolor.cgcolor]      //3 - set color space     let colorspace = cgcolorspacecreatedevicergb()      //4 - set color stops     let colorlocations:[cgfloat] = [0.0, 1.0]      //5 - create gradient     let gradient = cggradientcreatewithcolors(colorspace,         colors,         colorlocations)      //6 - draw gradient     var startpoint = cgpoint.zeropoint     var endpoint = cgpoint(x:0, y:self.bounds.height)     cgcontextdrawlineargradient(context,         gradient,         startpoint,         endpoint,         .drawsbeforestartlocation)      //calculate x point      let rightmargin:cgfloat = 40     let leftmargin : cgfloat = 10     let columnxpoint = { (column:int) -> cgfloat in         //calculate gap between points         let spacer = (width - rightmargin - leftmargin - 4) /             cgfloat((self.graphpoints.count - 1))         var x:cgfloat = cgfloat(column) * spacer         x += leftmargin + 2         print(x)         return x     }      // calculate y point      let topborder:cgfloat = 30     let bottomborder:cgfloat = 50     let graphheight = height - topborder - bottomborder     let maxvalue = graphpoints.maxelement()     let columnypoint = { (graphpoint:int) -> cgfloat in         var y:cgfloat = cgfloat(graphpoint) /             cgfloat(maxvalue!) * graphheight         y = graphheight + topborder - y // flip graph         print(y)         return y     }      // draw line graph      uicolor.whitecolor().setfill()     uicolor.whitecolor().setstroke()      //set points line     let graphpath = uibezierpath()     //go start of line     graphpath.movetopoint(cgpoint(x:columnxpoint(0), y:columnypoint(graphpoints[0])))      //add points each item in graphpoints array     //at correct (x, y) point     in 1..<graphpoints.count {         let nextpoint = cgpoint(x:columnxpoint(i),             y:columnypoint(graphpoints[i]))         graphpath.addlinetopoint(nextpoint)     }      //create clipping path graph gradient      //1 - save state of context (commented out now)     cgcontextsavegstate(context)      //2 - make copy of path     let clippingpath = graphpath.copy() as! uibezierpath      //3 - add lines copied path complete clip area     clippingpath.addlinetopoint(cgpoint(         x: columnxpoint(graphpoints.count - 1),         y:height))     clippingpath.addlinetopoint(cgpoint(         x:columnxpoint(0),         y:height))     clippingpath.closepath()      //4 - add clipping path context     clippingpath.addclip()      let highestypoint = columnypoint(maxvalue!)     startpoint = cgpoint(x:leftmargin, y: highestypoint)     endpoint = cgpoint(x:rightmargin, y:self.bounds.height)      cgcontextdrawlineargradient(context, gradient, startpoint, endpoint, .drawsbeforestartlocation)     cgcontextrestoregstate(context)      //draw line on top of clipped gradient     graphpath.linewidth = 2.0     graphpath.stroke()      //draw circles on top of graph stroke     in 0..<graphpoints.count {         var point = cgpoint(x:columnxpoint(i), y:columnypoint(graphpoints[i]))         point.x -= 5.0/2         point.y -= 5.0/2          let circle = uibezierpath(ovalinrect:             cgrect(origin: point,                 size: cgsize(width: 5.0, height: 5.0)))         circle.fill()     }        //draw horizontal graph lines on top of     let linepath = uibezierpath()      //top line     linepath.movetopoint(cgpoint(x:leftmargin, y: topborder))     linepath.addlinetopoint(cgpoint(x: width - rightmargin,         y:topborder))      //center line     linepath.movetopoint(cgpoint(x:leftmargin,         y: graphheight/2 + topborder))     linepath.addlinetopoint(cgpoint(x:width - rightmargin,         y:graphheight/2 + topborder))      //bottom line     linepath.movetopoint(cgpoint(x:leftmargin,         y:height - bottomborder))     linepath.addlinetopoint(cgpoint(x:width - rightmargin,         y:height - bottomborder))     let color = uicolor(white: 1.0, alpha: 0.3)     color.setstroke()      linepath.linewidth = 1.0     linepath.stroke()   } 

and here code view controller in pass data view.

import uikit import quartzcore  class progressviewcontroller: uiviewcontroller {   @iboutlet weak var graphview: uiview!   var firstgraph : graphview!   override func viewdidload() {  self.graphview = self.firstgraph   self.firstgraph = graphview(graphpoints: [2240, 1983, 2171, 2017, 1842, 1992, 2347]) 

i'm new swift , i'm stumped on problem after looking everywhere answer. appreciated.