What's the correct way to rotate a UILabel 90 degrees?

Question

I'm attempting to rotate a UILabel 90 degrees within a UIView.

The following snippet is an attempt to write something in Swift that can do that:

  //  #define DEGREES_TO_RADIANS(x) (x * M_PI/180.0)

    let angle:CGFloat = (90.0 * 3.14/180.0) as CGFloat
    let rotation = CGAffineTransformMakeRotation(angle)

    self.dayLabel.transform(rotation)

I encountered couple compiler errors:
1) Attempting to convert radians to an angle encountered a double --> float conversion problem and hence, had to use '3.14' vs 'M_Pi'.
2) I got the following error when attempting to actually doing the transformation on UILabel: enter image description here

What's the correct way to rotate a UILabel 90 degrees?

Okay... I got the transform syntax but...
Here's the original image:
enter image description here

My goal is to position 'TUE' vertically against the left side of the cell.
I originally tried a 90 deg counter rotation:

    self.dayLabel.transform = CGAffineTransformMakeRotation(-90)

And got the following:
enter image description here

I tried to vary the degrees but can't get a solid vertical position.
I do/can I have tighter control over the transformation?

Why use `transform` as a method and not assign it? Also, try using `CGFloat` constructor instead of casting to it. — DeFrenZ, Feb 04 '15 at 12:39

score 70 · Answer 1 · edited Mar 12 '20 at 13:42

70

Below code works in Swift 3, 4 and 5:

dayLabel.transform = CGAffineTransform(rotationAngle: .pi/2)

edited Mar 12 '20 at 13:42

Mohit Kumar

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answered Dec 23 '16 at 10:37

Mette

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4

You can also use `.pi / 2.0` instead of `CGFloat(M_PI_2)` in Swift 3. – Vadim Bulavin Jan 17 '17 at 12:43
1

But still you need to make it as `CGFloat` since `.pi` is `Double`. Thanks! – Mette Jan 17 '17 at 15:24
4

You're right that `.pi` is a member of `Double`, but it's also a member of `CGFloat` and `Float`: `Float.pi, Double.pi, CGFloat.pi` – Vadim Bulavin Jan 18 '17 at 11:59
because of this my view frame update (x:0,y:0,width:300,height:300) to (-62.132 -62.132; 424.264 424.264) – Kiran Sarvaiya Dec 21 '17 at 08:32

Matthew Usdin · Answer 2 · 2019-09-20T13:44:03.843

21

Try this way :

dayLabel.transform = CGAffineTransform(rotationAngle: .pi/2)

edited Sep 20 '19 at 13:44

answered May 19 '15 at 21:40

Matthew Usdin

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score 8 · Answer 3 · edited Feb 08 '16 at 19:13

8

self.dayLabel.transform = CGAffineTransformMakeRotation(M_PI_2)

Is the correct way to perform the transformation of 90 degrees, where M_PI_2 is the predefined radian value for 90 degrees.

edited Feb 08 '16 at 19:13

Myxtic

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answered Feb 04 '15 at 02:46

chris

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Need to cast mpi2 to float like so `CGFloat(M_PI_2)` – Alan Scarpa Jun 30 '16 at 20:36
because of this my view frame update (x:0,y:0,width:300,height:300) to (-62.132 -62.132; 424.264 424.264) – Kiran Sarvaiya Dec 21 '17 at 08:33
M_PI_2 is now deprecated, you can use .pi / 2 instead – WaleedAmmari Sep 15 '19 at 21:31

score 8 · Answer 4 · answered Jul 27 '18 at 15:50

8

Swift 4 solution with degrees value:

let degrees : Double = -90; //the value in degrees
self.dayLabel.transform = CGAffineTransform(rotationAngle: CGFloat(degrees * .pi/180))

answered Jul 27 '18 at 15:50

Daphyduck

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score 8 · Answer 5 · answered Oct 29 '18 at 09:17

8

swift 4

@IBOutlet weak var ourView: UIView!

    ourView.transform = CGAffineTransform(rotationAngle: CGFloat(Double(-45) * .pi/180))
//i gave it -45 degree.

answered Oct 29 '18 at 09:17

Akbar Khan

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You might want to use `CGFloat.pi` here. – HenryRootTwo Dec 06 '18 at 19:40

rakeshbs · Answer 6 · 2015-02-04T03:30:59.237

2

UIView.transform is a property of the UIView not a function.
Try setting self.label.transform = CGAffineTransformMakeRotation(angle) instead.

For more information https://developer.apple.com/library/ios/documentation/UIKit/Reference/UIView_Class/#//apple_ref/occ/instp/UIView/transform

edited Feb 04 '15 at 03:30

answered Feb 04 '15 at 02:47

rakeshbs

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score 1 · Answer 7 · answered Apr 11 '22 at 12:55

To ease calculation between radians and degrees forth and back I would even suggest to use the measurement API, which offers such built in:

let measurement = Measurement<UnitAngle>(value: 90.0, unit: .degrees)
let angleInRadians = measurement.converted(to: .radians).value
label.transform = CGAffineTransform(rotationAngle: angleInRadians)

score 0 · Answer 8 · answered Nov 15 '19 at 06:02

0

dayLabel.transform = dayLabel.transform.rotated(by: .pi / 2)

answered Nov 15 '19 at 06:02

Booharin

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score 0 · Answer 9 · answered Dec 05 '20 at 14:02

func rotate(button: UIButton) {
let angles = [CGFloat(Double(270) * .pi/180),
              CGFloat(Double(180) * .pi/180),
              CGFloat(Double(90) * .pi/180),
              CGFloat(Double(0) * .pi/180)
]
for i in 0..<4 {
    UIView.animate(withDuration: 0.125, delay: 0.125 * Double(i), animations: {
        button.transform = CGAffineTransform(rotationAngle: angles[i])
    }, completion: nil)
}

score -8 · Answer 10 · answered Feb 04 '15 at 04:53

-8

Apparently I have adjust down to the 1/100 of a counter degree to nudge it vertical:

self.dayLabel.transform = CGAffineTransformMakeRotation(-89.55)

The result:
enter image description here

answered Feb 04 '15 at 04:53

Frederick C. Lee

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It is clear from the documentation that `CGAffineTransformMakeRotation` gets an angle in radians as a parameter, you just happened to find an angle which looked quite similar to what you wanted. – DeFrenZ Feb 04 '15 at 12:39

What's the correct way to rotate a UILabel 90 degrees?

10 Answers10