UIImage+NKOGraphics.h

// make image from color

#import <UIKit/UIKit.h>

@interface UIImage (NKOGraphics)

+ (UIImage*)nko_imageWithColor:(UIColor*)color;
+ (UIImage*)nko_imageWithColor:(UIColor*)color size:(CGSize)size;
+ (UIImage*)nko_imageWithColor:(UIColor*)color size:(CGSize)size cornerRadius:(CGFloat)radius;
+ (UIImage*)nko_gradientImageWithTopColor:(UIColor*)topColor bottomColor:(UIColor*)bottomColor size:(CGSize)size radius:(CGFloat)radius;

@end

UIImage+NKOGraphics.m

#import "UIImage+NKOGraphics.h"

@implementation UIImage (NKOGraphics)

+ (UIImage*)nko_imageWithColor:(UIColor*)color
{   
    return [self nko_imageWithColor:color size:CGSizeMake(1, 1)];
}

+ (UIImage*)nko_imageWithColor:(UIColor*)color size:(CGSize)size
{
    CGRect rect = {
        .origin = CGPointZero,
        .size = size
    };
    
    UIGraphicsBeginImageContext(rect.size);
    CGContextRef context = UIGraphicsGetCurrentContext();
    
    [color setFill];
    CGContextFillRect(context, rect);
    
    UIImage* image = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();
    
    return image;
}

+ (UIImage*)nko_imageWithColor:(UIColor*)color size:(CGSize)size cornerRadius:(CGFloat)radius
{
    CGRect rect = {
        .origin = CGPointZero,
        .size = size
    };
    
    NSAssert(size.width > radius*2 && size.height > radius*2, @"Radius is bigger than expected");
    
    UIGraphicsBeginImageContext(rect.size);
    CGContextRef context = UIGraphicsGetCurrentContext();
    
    UIBezierPath* path = [UIBezierPath bezierPathWithRoundedRect:rect cornerRadius:radius];
    [path addClip];
    
    [color setFill];
    CGContextAddPath(context, [path CGPath]);
    CGContextFillPath(context);
    
    UIImage* image = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();
    
    return image;
}

+ (UIImage*)nko_gradientImageWithTopColor:(UIColor*)topColor bottomColor:(UIColor*)bottomColor size:(CGSize)size radius:(CGFloat)radius
{
    CGRect rect = {
        .origin = CGPointZero,
        .size = size
    };
    
    NSAssert(size.width > radius*2 && size.height > radius*2, @"Radius is bigger than expected");
    
    UIGraphicsBeginImageContext(rect.size);
    CGContextRef context = UIGraphicsGetCurrentContext();
    
    CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();
    CGFloat locations[2] = {0.0, 1.0};
    
    NSArray* gradientColors = @[(id)[topColor CGColor],
                                (id)[bottomColor CGColor]];
    CGGradientRef gradient = CGGradientCreateWithColors(colorSpace, (__bridge CFArrayRef)gradientColors, locations);
    CGColorSpaceRelease(colorSpace);
    
    UIBezierPath* path = [UIBezierPath bezierPathWithRoundedRect:rect cornerRadius:radius];
    [path addClip];
    
    CGContextAddPath(context, [path CGPath]);
    CGContextDrawLinearGradient(context, gradient, CGPointMake(0, 0), CGPointMake(0, rect.size.height), kCGGradientDrawsAfterEndLocation);
    CGGradientRelease(gradient);
    
    UIImage* image = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();
    
    return image;
}


@end