Make a blank UI image with a given size, and optional fill color

UIImage+Extensions.h

#import <Foundation/Foundation.h>

@interface UIImage (Extensions)

+ (UIImage*)blankImage:(CGSize)_size;
+ (UIImage*)blankImage:(CGSize)_size withColor:(UIColor*)_color;

@end

UIImage+Extensions.m

#import "UIImage+Extensions.h"

@implementation UIImage (Extensions)

+ (UIImage*)blankImage:(CGSize)_size {
    return [self blankImage:_size withColor:nil];
}

+ (UIImage*)blankImage:(CGSize)_size withColor:(UIColor*)_color {
    if (!_color) {
        _color = [UIColor clearColor];
    }
    UIGraphicsBeginImageContext(_size);  
	CGContextRef context = UIGraphicsGetCurrentContext();
    CGContextSetFillColorWithColor(context, _color.CGColor);
    CGContextFillRect(context, CGRectMake(0.0, 0.0, _size.width, _size.height));
    UIImage* outputImage = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();
    return outputImage;
}

@end