Drawing gradient over image in ios

Question

How to create gradient colour look like following image programatically.

Answer 1

-(void) drawGradientinBounds: (CGRect) currentBounds withColors:(NSArray*) colors andPercentages:(NSArray *)percentages andGradientDirectionIsVertical:(BOOL)isGradientDirectionVertical
{

    CGContextRef currentContext = UIGraphicsGetCurrentContext();

    CGGradientRef glossGradient;
    CGColorSpaceRef rgbColorspace;

    size_t num_locations = [percentages count];
    CGFloat locations[num_locations];
    for(int i=0;i=0;i--)
    {
        comps--;
        UIColor *c = [colors objectAtIndex:i];
        const CGFloat *cg = CGColorGetComponents([c CGColor]);
        components[comps] = cg[3];
        comps--;
        components[comps] = cg[2];
        comps--;
        components[comps] = cg[1];
        comps--;
        components[comps] = cg[0];
    }

    rgbColorspace = CGColorSpaceCreateDeviceRGB();
    glossGradient = CGGradientCreateWithColorComponents(rgbColorspace, components, locations, num_locations);

    CGPoint topCenter;
    CGPoint endCenter;

    if(isGradientDirectionVertical)
    {
        topCenter = CGPointMake(CGRectGetMidX(currentBounds), currentBounds.origin.y);
        endCenter = CGPointMake(CGRectGetMidX(currentBounds), CGRectGetHeight(currentBounds)+currentBounds.origin.y);

    }
    else
    {
        topCenter = CGPointMake( currentBounds.origin.x,CGRectGetMidY(currentBounds));
        endCenter = CGPointMake(CGRectGetWidth(currentBounds)+currentBounds.origin.x,CGRectGetMidY(currentBounds));
    }
    CGContextDrawLinearGradient(currentContext, glossGradient, topCenter, endCenter, 0);

    CGGradientRelease(glossGradient);
    CGColorSpaceRelease(rgbColorspace);
}

And the input to this method are bounds, colorArray:

[NSArray arrayWithObjects:[UIColor blackColor], [UIColor whiteColor], nil]

percentageArray:

[NSArray arrayWithObjects:[NSNumber numberWithFloat:0.0], [NSNumber numberWithFloat:1.0], nil]