how to move an UIImageview from point A to B in a certain degree

Question

I would like to move a UIImageview from point A to B in certain degree. the Red and Blue arrow denote the degree i want the dots to move.

i can move the dots from one point to another, but how do i move the note on a degree ?

    NSLog(@"cgpoint %@",NSStringFromCGPoint(self.aggressiveDots.frame.origin)); 
CAKeyframeAnimation *anim = [CAKeyframeAnimation animationWithKeyPath:@"position"]; 
NSArray *times = [NSArray arrayWithObjects:[NSNumber numberWithFloat:0.0], nil];
[anim setKeyTimes:times];   
NSArray *values = [NSArray arrayWithObjects:[NSValue valueWithCGPoint:CGPointMake(118, 188.)],
                   [NSValue valueWithCGPoint:CGPointMake(115, 300.)], nil];
[anim setValues:values];
[anim setDuration:6.0]; //seconds    
[self.redDots.layer addAnimation:anim forKey:@"position"];

enter image description here

@rmaddy attached 2nd pic. Would like to move the red dot towards the white dot — Desmond, Nov 04 '13 at 04:30
If you know the two points, simply animate the change in frame using `UIView animateWithDuration:delay:options:animations:completion:` or one of its variations. I still don't understand the question. If you know how to move the dots from one point to another, what part don't you know? — rmaddy, Nov 04 '13 at 04:32

score 1 · Accepted Answer · edited May 23 '17 at 12:02

Since you'd like to move the UIView along a straight line (not a curve) you only need two points for your CAKeyFrameAnimation - the starting and endoing point. In fact you could even use [UIView transistionWithView:] for this if you wanted - just manipulate the frame in the animation block.

You already know the starting point.
To calculate the ending point you need to find the point where the edge of the red circle intersects the white circle. There's an equation to solve the intersection points of two circles detailed here

If you'd like to avoid tricky algebra, you can draw a triangle as follows:

Just let the first circle travel down the line, using the simple line equation y=mx + b
Test if the edge of the circle (which is radius points along the line ahead of the center) is inside the triangle using the formula outlined here

"In general, x and y must satisfy (x - center_x)^2 + (y - center_y)^2 < radius^2"

how to move an UIImageview from point A to B in a certain degree

1 Answers1