CALayer background color - ios

Question

I have a CALayer background using:
CAGradientLayer *bgLayer = [BackgroundLayer blueGradient];
bgLayer.frame = self.view.bounds;
[self.view.layer insertSublayer:bgLayer atIndex:0];
In
- (void)prepareToRotate:(UIInterfaceOrientation)toInterfaceOrientation duration:(NSTimeInterval)duration
I use this line to rotate the CALayer background.
[[[self.view.layer sublayers] objectAtIndex:0] setFrame:self.view.bounds];
I am getting some tearing effects that are not pretty as the layer seemingly doesn't rotate fast enough, how can I fix this and get a seamless effect on rotate, is there a better way to resize the calayer?
Thanks,
EDIT: All my code:
the .h:
#import <Foundation/Foundation.h>
#import <QuartzCore/QuartzCore.h>
#interface BackgroundLayer : NSObject
+(CAGradientLayer*) greyGradient;
+(CAGradientLayer*) blueGradient;
#end
the .m
#import "BackgroundLayer.h"
#implementation BackgroundLayer
//Metallic grey gradient background
+ (CAGradientLayer*) greyGradient {
UIColor *colorOne = [UIColor colorWithWhite:0.9 alpha:1.0];
UIColor *colorTwo = [UIColor colorWithHue:0.625 saturation:0.0 brightness:0.85 alpha:1.0];
UIColor *colorThree = [UIColor colorWithHue:0.625 saturation:0.0 brightness:0.7 alpha:1.0];
UIColor *colorFour = [UIColor colorWithHue:0.625 saturation:0.0 brightness:0.4 alpha:1.0];
NSArray *colors = [NSArray arrayWithObjects:(id)colorOne.CGColor, colorTwo.CGColor, colorThree.CGColor, colorFour.CGColor, nil];
NSNumber *stopOne = [NSNumber numberWithFloat:0.0];
NSNumber *stopTwo = [NSNumber numberWithFloat:0.02];
NSNumber *stopThree = [NSNumber numberWithFloat:0.99];
NSNumber *stopFour = [NSNumber numberWithFloat:1.0];
NSArray *locations = [NSArray arrayWithObjects:stopOne, stopTwo, stopThree, stopFour, nil];
CAGradientLayer *headerLayer = [CAGradientLayer layer];
headerLayer.colors = colors;
headerLayer.locations = locations;
return headerLayer;
}
//Blue gradient background
+ (CAGradientLayer*) blueGradient {
UIColor *colorOne = [UIColor colorWithRed:(120/255.0) green:(135/255.0) blue:(150/255.0) alpha:1.0];
UIColor *colorTwo = [UIColor colorWithRed:(57/255.0) green:(79/255.0) blue:(96/255.0) alpha:1.0];
NSArray *colors = [NSArray arrayWithObjects:(id)colorOne.CGColor, colorTwo.CGColor, nil];
NSNumber *stopOne = [NSNumber numberWithFloat:0.0];
NSNumber *stopTwo = [NSNumber numberWithFloat:1.0];
NSArray *locations = [NSArray arrayWithObjects:stopOne, stopTwo, nil];
CAGradientLayer *headerLayer = [CAGradientLayer layer];
headerLayer.colors = colors;
headerLayer.locations = locations;
return headerLayer;
}
#end
Prepare to rotate is simply called by
- (void)didRotateFromInterfaceOrientation:(UIInterfaceOrientation)fromInterfaceOrientation
{
[self prepareToRotate:[[UIApplication sharedApplication] statusBarOrientation] duration:0];
}
and just contains
[[[self.view.layer sublayers] objectAtIndex:0] setFrame:self.view.bounds];

Answer 1

I'd recommend to use CAGradientLayer over CoreGraphics. It is much faster to render. For your issue, try to rasterize your view before the rotation.
- (void)willRotateToInterfaceOrientation:(UIInterfaceOrientation)toInterfaceOrientation duration:(NSTimeInterval)duration
{
self.bgLayer.shouldRasterize = YES;
}
Actually, you can add a subview instead of a new layer.
#interface MyView : UIView
#end
#implementation MyView
+ (Class)layerClass
{
return [CAGradientLayer class];
}
#end
In your old inserting layer part, do following instead.
MyView *bgView = [[MyView alloc] initWithFrame:self.view.bounds];
[(CAGradientLayer *)bgView.layer setColors:colors];
bgView.autoresizingMask = UIViewAutoresizingFlexibleHeight | UIViewAutoresizingFlexibleWidth;
[self.view insertSubview:bgView atIndex:0];
(You can use auto-layout if you want)

Answer 2

Coregraphics gradient layers are much better then CALayer. CALayer is slow and will show the gradient bands while coregraphics will have a smooth gradient. This is probably why it is happening to you.
Create a -(void)drawRect:(CGRect)rect { function and draw your gradient under there. It should take care of your issue.
There is a lot of sample code out there for this. Here is some
CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();
CGFloat locations[] = { 0.0, 1.0 };
NSArray *colors = #[(__bridge id) startColor, (__bridge id) endColor];
CGGradientRef gradient = CGGradientCreateWithColors(colorSpace, (__bridge CFArrayRef) colors, locations);