Blure Effect

Adding blur effect on the view's corner

User interface play an important role in development of a good application. With the useful and important features, it is necessity of a application to make a attractive and good looking user interface. A well design interface force user to play with application and enjoy the application for a time being.

A small small effect can make the interface better like presenting sub-view  with animation or bounce, adding blur effect in the corner of sub-views.
Here i am going to add blur effect in the corner of sub views.
We can achieve blur effect by using gradient. We are having in-build CAGraientLayer in iOS, so its not a tough  to add blur effect in both corner of a view, because of this CAGraientLayer.
Click here for details of CAGraientLayer.

First create a project and add a UIView as a subview of view in the storyboard or xib file.
Than go to .h file and create a outlet for added UIView.

@property (nonatomic, weak) IBOutlet UIView *horizontalLineViewFirst;

again go to storyboard  or xib file and connect the outlet to added UIView.

Now switch to .m file and add a method

#pragma mark - Add Gradient
-(void) addGrandientlayerToView:(UIView *)gradientView{
    //create a gradient layer
    CAGradientLayer *gradientLayer = [CAGradientLayer layer];
    //set gradient color
    CGColorRef outerColor = [[UIColor colorWithWhite:0.97 alpha:1.0] CGColor];
    CGColorRef innerColor = [[UIColor colorWithWhite:0.72 alpha:0.0] CGColor];
    //set name of the layer
    gradientLayer.name = @"BlurGradientLayer";
    //set color to gradien layer
    gradientLayer.colors = [NSArray arrayWithObjects:(__bridge id)outerColor,(__bridge id)innerColor,(__bridge id)innerColor,(__bridge id)outerColor, nil];
    //set location to each color
    gradientLayer.locations = [NSArray arrayWithObjects:[NSNumber numberWithFloat:0.0],[NSNumber numberWithFloat:0.200],[NSNumber numberWithFloat:0.710],[NSNumber numberWithFloat:1.0], nil];
    //set start point for draw a gradient layer
    [gradientLayer setStartPoint:CGPointMake(0, 0.6)];
    //set start point for draw a gradient layer
    [gradientLayer setEndPoint:CGPointMake(1, 0.6)];
    //set bound of the layer
    gradientLayer.bounds = gradientView.bounds;
    //set anchor point of layer to {0,0}
    gradientLayer.anchorPoint = CGPointZero;
    [gradientView.layer addSublayer:gradientLayer];
}

pass the message to above method form viewDidLoad method

[self addGrandientlayerToView:self.horizontalLineViewFirst];

Run the  app,  we can see a blur effect on added subview.

 

We can see a effect similar to above image a horizontal line with blur corners.

Now rotate the simulator or device,  one side of blur effect get misplace,its come in the middle not in both corners. Lets fix the issue

add another method to reset gradient location after orientation

#pragma mark -
#pragma mark Handle Orientation
- (void) handleOrientationChange:(NSNotification *)notification{
    [self resetAllGradientLayer];
}
-(void) resetAllGradientLayer{
    [self resetGradientforView:self.horizontalLineViewFirst];
}
-(void) resetGradientforView:(UIView *)gradientView{
    for (CAGradientLayer *layer in gradientView.layer.sublayers){
        if ([layer.name isEqualToString:@"BlurGradientLayer"]) {
            layer.bounds = gradientView.bounds;
        }
    }
}
 
Add orientation change notification to controller

[[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(handleOrientationChange:) name:UIDeviceOrientationDidChangeNotification object:nil];

 
Now again run the application and check.
Click here for complete project.

Drawing on iOS

Drawing with Quartz and UIKit:

Quartz is the native drawing technology in iOS. Core Graphics framework is at the heart of Quartz and is the primary interface use for drawing content. Quartz 2D is a two-dimensional drawing engine which is use of such as path based drawing,  painting with transparency, shading, drawing shadows, transparency layers, color management, anti aliased rendering, PDF documents generation, and PDF metadata access.

Configuring the Graphics Context:
View object create a graphics context and sets it as the current context. This context exists only for the the lifetime of the drawRect: call. For retrieve a pointer to this graphics context we can call UIGraphicsGetCurrentContext function. This function returns a reference to a CGContextRef type, which pass to core graphics function to modify the current graphics state. The graphics context contains a stack for save graphics states. When Quartz creates a graphics context, the stack is empty. Using CGContextSaveState function pushes a copy of the current graphics state onto the stack. Modification make to graphics state affect subsequent drawing operations but do not affect the copy stored on the slack.with done of modification we can return to the previous graphics state by popping the saved state off the top of the stack using the CGContextRestoreGState function. Pushing and popping graphics states in this manner is a fast way to return to a previous state.For Details Click here


Drawing:
//Draw a line
In order to draw graphics on the view it is necessary to subclass to create a subclass of UIView and override the drawRect: method.

Lets subclass a UIView(named LineView)

Now override drawRect: method

- (void)drawRect:(CGRect)rect {
    // Drawing code
    CGContextRef context = UIGraphicsGetCurrentContext(); //Get current graphics context
    CGContextSaveGState(context); //Save current context
    CGContextSetLineWidth(context, lineWidth); // set stroke width of line
    CGContextSetStrokeColorWithColor(context, [[UIColor redColor] CGColor]); //set stroke color
    CGContextMoveToPoint(context, 10,  10); // It is the first point of line
    CGContextAddLineToPoint(context, self.bounds.size.width - 10, 10); // set another point of line
    CGContextStrokePath(context); // stroke line
    CGContextRestoreGState(context);
}
Import newly added subclass to ViewController and add as a subview to the ViewController's view.


//Draw a Rectangle
subclass a UIView(named LineView)
and override drawRect: method

- (void)drawRect:(CGRect)rect {
    // Drawing code
    CGContextRef context = UIGraphicsGetCurrentContext();
    CGContextSaveGState(context);
    CGContextSetLineWidth(context, lineWidth);
    CGContextSetStrokeColorWithColor(context, [[UIColor redColor] CGColor]);
    CGContextMoveToPoint(context, 10,  10); // start point
    CGContextAddLineToPoint(context, self.bounds.size.width - 10, 10);
    CGContextAddLineToPoint(context, self.bounds.size.width - 10, self.bounds.size.height - 10);
    CGContextAddLineToPoint(context,  10, self.bounds.size.height - 10);
    CGContextAddLineToPoint(context, 10, 10);
    CGContextStrokePath(context);
   CGContextRestoreGState(context);
}