How can I rotate an UIImageView by 20 degrees?

Question

What do I have to do, if I need to rotate a UIImageView? I have a UIImage which I want to rotate by 20 degrees.

The Apple docs talk about a transformation matrix, but that sounds difficult. Are there any helpful methods or functions to achieve that?

score 114 · Answer 1 · edited Oct 09 '18 at 08:26

114

If you want to turn right, the value must be greater than 0 if you want to rotate to the left indicates the value with the sign "-". For example -20.

CGFloat degrees = 20.0f; //the value in degrees
CGFloat radians = degrees * M_PI/180;
imageView.transform = CGAffineTransformMakeRotation(radians);

Swift 4:

let degrees: CGFloat = 20.0 //the value in degrees
let radians: CGFloat = degrees * (.pi / 180)
imageView.transform = CGAffineTransform(rotationAngle: radians)

edited Oct 09 '18 at 08:26

Olcay Ertaş

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answered Mar 15 '12 at 10:46

alexmorhun

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This should be ticked, its the best answer by far! – Supertecnoboff May 20 '15 at 14:12
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Degrees conversion is a really nice plus, this should be the best one! – Liam Bolling Jan 13 '16 at 18:30
Absolutely the best! – skg May 28 '19 at 07:37

score 93 · Accepted Answer · edited Jan 11 '20 at 20:02

93

A transformation matrix is not incredibly difficult. It's quite simple, if you use the supplied functions:

imgView.transform = CGAffineTransformMakeRotation(.34906585);

(.34906585 is 20 degrees in radians)

Swift 5:

imgView.transform = CGAffineTransform(rotationAngle: .34906585)

edited Jan 11 '20 at 20:02

nevos

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answered May 12 '09 at 13:47

Ed Marty

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Thanks! And I really thought it's complicated, just because of the "transform matrix" ;) – Thanks May 12 '09 at 13:54

score 10 · Answer 3 · answered Nov 28 '15 at 09:22

10

Swift version:

let degrees:CGFloat = 20
myImageView.transform = CGAffineTransformMakeRotation(degrees * CGFloat(M_PI/180) )

answered Nov 28 '15 at 09:22

Frank Eno

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The same code (except let) will work for objective-c too. – Onur Tuna Jun 15 '16 at 11:00

score 5 · Answer 4 · answered Oct 31 '17 at 09:09

5

Swift 4.0

imageView.transform = CGAffineTransform(rotationAngle: CGFloat(20.0 * Double.pi / 180))

answered Oct 31 '17 at 09:09

William Hu

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score 2 · Answer 5 · answered Jul 25 '17 at 15:38

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Here's an extension for Swift 3.

extension UIImageView {

    func rotate(degrees:CGFloat){
        self.transform = CGAffineTransform(rotationAngle: degrees * CGFloat(M_PI/180))
      }  
    }

Usage:

myImageView.rotate(degrees: 20)

answered Jul 25 '17 at 15:38

JP Aquino

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score 1 · Answer 6 · answered Jan 20 '17 at 16:19

1

This is an easier formatting example (for 20 degrees):

CGAffineTransform(rotationAngle: ((20.0 * CGFloat(M_PI)) / 180.0))

answered Jan 20 '17 at 16:19

Alex Bailey

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score 1 · Answer 7 · answered Jul 04 '11 at 09:55

1

_YourImageView.transform = CGAffineTransformMakeRotation(1.57);

where 1.57 is the radian value for 90 degree

answered Jul 04 '11 at 09:55

Radix

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score -2 · Answer 8 · answered May 12 '09 at 13:46

-2

As far as I know, using the matrix in UIAffineTransform is the only way to achieve a rotation without the help of a third-party framework.

answered May 12 '09 at 13:46

Marc W

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How can I rotate an UIImageView by 20 degrees?

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