how to rotate UIIMageVIew with fix point?

Question

I want to rotate image on angle.But i wnt to rotate image with fix point.How can i set this fix point?

Answer 1

Set the view's layer's anchorpoint, which is in view-local coordinates from 0 to 1. That is, the top left is 0,0 and the bottom right is 1,1.

For example, the default is to rotate around the center:

imageView.layer.anchorPoint = CGPointMake(.5,.5);

If you want to rotate around the origin:

imageView.layer.anchorPoint = CGPointMake(0,0);

Or the middle right edge:

imageView.layer.anchorPoint = CGPointMake(1,.5);

Answer 2

If you create a project using the default "View-based Application" in Xcode, just add this code to your -viewDidLoad in the main view controller that it creates:

- (void)viewDidLoad {
    [super viewDidLoad];

    CABasicAnimation *rotationAnimation = [CABasicAnimation 
                         animationWithKeyPath:@"transform.rotation.z"];

    [rotationAnimation setFromValue:DegreesToNumber(0)];
    [rotationAnimation setToValue:DegreesToNumber(360)];
    [rotationAnimation setDuration:3.0f];
    [rotationAnimation setRepeatCount:10000];

    [[[self view] layer] addAnimation:rotationAnimation forKey:@"rotate"];
}

This will rotate the view around the x axis (center by default). You can just set the contents of that view (e.g. [[self view] setContents:image] where image is an image that you load using UIImage).

Here are my helper functions for converting degrees to radians.

CGFloat DegreesToRadians(CGFloat degrees)
{
    return degrees * M_PI / 180;
}

NSNumber* DegreesToNumber(CGFloat degrees)
{
    return [NSNumber numberWithFloat:
            DegreesToRadians(degrees)];
}

Hope that helps.