How to programmatically rotate the view by 180 degrees on iOS?

Question

How to programmatically rotate the view by 180 degrees in my iPhone App?

score 36 · Answer 1 · edited Aug 26 '17 at 21:17

As ’CGAffineTransformRotate’ uses radians as its unit of measure, and 180 degrees is the same as PI, instead of the math provided in other answers you can simply do:

view.transform = CGAffineTransformRotate(view.transform, M_PI);

Swift 3:

view.transform = view.transform.rotated(by: .pi)

If you plan on doing a lot of transforms, it's probably best to read up on radians, so you understand what is going on.

score 14 · Accepted Answer · edited May 23 '17 at 11:55

14

Should be possible by using CGAffineTransform

Quote from this question, this should do the trick:

CGFloat radians = atan2f(yourView.transform.b, yourView.transform.a);
CGFloat degrees = radians * (180 / M_PI);
CGAffineTransform transform = CGAffineTransformMakeRotation((90 + degrees) * M_PI/180);
yourView.transform = transform;

edited May 23 '17 at 11:55

Community

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answered Jul 25 '11 at 09:17

Manny

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This rotates it 90 degrees. If you want it to rotate it by 180 degrees, they last line should be `CGAffineTransformMakeRotation((` **180** `+ degrees) * M_PI/180)` instead of 90 – Eliza Wilson May 14 '14 at 00:39

score 8 · Answer 3 · answered Nov 29 '17 at 19:38

Swift 4:

self.view.transform = CGAffineTransform(rotationAngle: .pi);

And a COMMENT (I evidently don't have enough points to enter my comment on his/her answer) for Benjamin Mayo or vtcajones answer of:

view.transform = view.transform.rotated(by: .pi)

This will work the first time, but the next time it is called it will rotate the view again, back to the original rotation, which is probably not what you want. It would be safer to set the transform value exactly each time.

score 6 · Answer 4 · edited May 31 '16 at 12:42

6

Simple solution:

view.transform = CGAffineTransformMakeRotation(degrees*M_PI/180);

edited May 31 '16 at 12:42

Just Shadow

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answered Sep 02 '13 at 12:32

Ram Vadranam

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score 5 · Answer 5 · answered Jan 09 '17 at 20:47

5

In Swift 3 :

let rotationDegrees =  180.0
let rotationAngle = CGFloat(rotationDegrees * M_PI / 180.0)
view.transform = CGAffineTransform(rotationAngle: rotationAngle)

answered Jan 09 '17 at 20:47

Wilson

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score 4 · Answer 6 · edited Dec 18 '15 at 22:21

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Same outcome as @Manny's answer using a different function.

 CGFloat degreesOfRotation = 180.0;
 view.transform = CGAffineTransformRotate(view.transform,
     degreesOfRotation * M_PI/180.0);

edited Dec 18 '15 at 22:21

cbay

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answered Jul 25 '11 at 09:44

thealch3m1st

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score 1 · Answer 7 · answered Aug 21 '17 at 22:10

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Latest Swift 3 syntax:

view.transform = view.transform.rotated(by: .pi)

answered Aug 21 '17 at 22:10

vtcajones

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How to programmatically rotate the view by 180 degrees on iOS?

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