ios - giving an ImageView circular bounds? -

i using imageview render circular gradient selecting color.

the problem is, long pangesturerecognizer remains inside rectangular imageview, continue returning colors when outside of circular gradient.

is there way enforce circular bounds?

here code adding gradient imageview :

cgsize size = cgsizemake(self.view.bounds.size.width, ((self.view.bounds.size.height)/2)); uigraphicsbeginimagecontextwithoptions(cgsizemake(size.width, size.height), yes, 0.0); [[uicolor whitecolor] setfill]; uirectfill(cgrectmake(0, 0,size.width,size.height));   int sectors = 180; float radius = min(size.width, size.height)/2; float angle = 2 * m_pi/sectors; uibezierpath *bezierpath; ( int = 0; < sectors; i++) {     cgpoint center = cgpointmake(((size.width)/2), ((size.height)/2));     bezierpath = [uibezierpath bezierpathwitharccenter:center radius:radius startangle:i * angle endangle:(i + 1) * angle clockwise:yes];     [bezierpath addlinetopoint:center];     [bezierpath closepath];     uicolor *color = [uicolor colorwithhue:((float)i)/sectors saturation:1. brightness:1. alpha:1];     [color setfill];     [color setstroke];     [bezierpath fill];     [bezierpath stroke]; } img = uigraphicsgetimagefromcurrentimagecontext(); gradientview = [[uiimageview alloc]initwithimage:img];; 

you should check if touch inside of imaginary circle.

all need pretty basic trigonometry. need calculate distance between touch point , center of view. if distance bigger radius of colorview want return without changing new color (or set value @ edge of colorview)

i use hue , saturation picker.

- (void)gesturerecognizerdidpan:(uipangesturerecognizer *)gesture {     cgfloat saturation = 0.0f;     cgfloat hue = 0.0f;      uiview *colorview = gesture.view;     cgpoint location = [gesture locationinview:colorview];      // assume colored area circle inside of square rect     cgpoint colorviewcenter = cgpointmake(ceilf(cgrectgetwidth(colorview.bounds)/2.0f), ceilf(cgrectgetheight(colorview.bounds)/2.0f));     cgfloat colorviewradius = floorf(cgrectgetwidth(colorview.bounds)/2.0f);      cgfloat dx = location.x - colorviewcenter.x;     cgfloat dy = location.y - colorviewcenter.y;     cgfloat touchradius = sqrtf(powf(dx, 2)+powf(dy, 2));     if (touchradius > colorviewradius) {         // touch outside of circular area          // set saturation max         saturation = 1.0f;          // or:          // return;     }     else {         saturation = touchradius / colorviewradius;     }      cgfloat anglerad = atan2f(dx, dy);     cgfloat angledeg = (anglerad * (180.0f/m_pi) - 90);     if (angledeg < 0.f) {         angledeg += 360.f;     }     hue = angledeg / 360.0f;      // tell target }