BisonCreative & development notes

UIKit & graphicsHistorical technical note

Animating a view around another view on iOS

Explains how to move a view around the centre of an image. Trigonometric functions calculate points on a circle, and updating the view coordinates produces an orbiting animation without a complex animation framework.

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"Health is the foundation of everything. Getting more exercise is the way to go." Bison

A recent project needed an animation, so I looked through a lot of related material.
I found nothing suitable, so I made a custom implementation.
The main principle uses the sine rule for triangles
and the cosine rule to animate a view moving around an image's center.

See the code below.

Core code

self.center = CGPointMake(_radius * cosf(_angle) + imgView.center.x, _radius * sinf(_angle) + imgView.center.y);

_timer = [NSTimer scheduledTimerWithTimeInterval:_time target:self selector:@selector(moveView) userInfo:nil repeats:YES];

Click to download the demo

(RadiusOperation)