Rotary Control Blog 1

/*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*/

// Implement viewDidLoad to do additional setup after loading the view, typically from a nib.
- (void)viewDidLoad
{
    [super viewDidLoad];

    // Create a UIImageView with the circle image and center it in the main view.
    UIImageView *container = [[UIImageView alloc] initWithFrame:CGRectMake(0.0, 0.0f, 300.0f, 300.0f)];
    container.image = [UIImage imageNamed:@"CircleInSquare"];
    container.center = CGPointMake(self.view.bounds.size.width/2.0, self.view.bounds.size.height/2.0);
    [self.view addSubview:container];

    // Calculate the angle between each label based on the number of labels.
    int numberOfSections = 9;
    CGFloat angleSize = 2*M_PI/numberOfSections;

    // Each label gets the exact same inital frame, but a different transform is applied to space them around the circle.
    for (int i = 0; i < numberOfSections; ++i) {
        UILabel *sectionLabel = [[UILabel alloc] initWithFrame:CGRectMake(0.0f, 0.0f, 150.0f, 50.0f)];
        sectionLabel.text = [NSString stringWithFormat:@"%i", i];
        sectionLabel.font = [UIFont systemFontOfSize:50.0];
        sectionLabel.textColor = [UIColor whiteColor];
        sectionLabel.backgroundColor = [UIColor clearColor];
        //sectionLabel.backgroundColor = [UIColor colorWithRed:1.0f green:0.0f blue:0.2f alpha:0.5f];

        /***** Here's the most important part: changing the anchorPoint, adjusting the position accordingly, and applying rotation ****/
        sectionLabel.layer.anchorPoint = CGPointMake(1.0f, 0.5f);
        sectionLabel.layer.position = CGPointMake(container.bounds.size.width/2.0, container.bounds.size.height/2.0); // places anchorPoint of each label directly in the center of the circle.
        sectionLabel.transform = CGAffineTransformMakeRotation(angleSize*i);
        [container addSubview:sectionLabel];
    }
}