Question

I am new to iOS and am doing this as a learning experience. I got most of this code from a tutorial and its working but I wanted to add more stroke colors. My code begins with a default stroke in UIColor greenColor, but I have two buttons labeled “Red” and “Blue” that should change the stroke color to Red or Blue when pressed. I want to press Red, then start drawing and have that stroke come out red, etc. like in MS Paint. I’ve confirmed my UIButtons are linked up correctly. Any help is appreciated, thanks!

DrawView.h:

#import <UIKit/UIKit.h>
@interface DrawView : UIImageView
- (void)changeOption:(NSString *)withOption;
@end

DrawView.m:

#import "DrawView.h"
@interface DrawView()
@property (nonatomic) BOOL fingerMoved;
@property (nonatomic) CGPoint lastPoint;
@end

@implementation DrawView

CGFloat red = 0.0, green = 0.0, blue = 0.0, width = 5.0;
@synthesize fingerMoved = _fingerMoved;
@synthesize lastPoint = _lastPoint;

- (id)initWithFrame:(CGRect)frame
{
    self = [super initWithFrame:frame];
    if (self) {
        // Initialization code
    }
    return self;
}

- (void)changeOption:(NSString *)withOption
{
    if ([withOption isEqualToString:@"Black"]) {
        red = 0.0; green = 0.0; blue = 0.0; width = 5.0;
    }else if ([withOption isEqualToString:@"Red"]) {
        red = 1.0; green = 0.0; blue = 0.0; width = 5.0;
    }else if ([withOption isEqualToString:@"Blue"]) {
        red = 0.0; green = 0.0; blue = 1.0; width = 5.0;
    }else if ([withOption isEqualToString:@"Green"]) {
        red = 0.0; green = 1.0; blue = 0.0; width = 5.0;
    }else if ([withOption isEqualToString:@"Brown"]) {
        red = 0.4; green = 0.0; blue = 0.0; width = 5.0;
    }else if ([withOption isEqualToString:@"Orange"]) {
        red = 1.0; green = 0.6; blue = 0.0; width = 5.0;
    }else if ([withOption isEqualToString:@"Yellow"]) {
        red = 1.0; green = 1.0; blue = 0.0; width = 5.0;
    }else if ([withOption isEqualToString:@"Purple"]) {
        red = 0.5; green = 0.0; blue = 1.0; width = 5.0;
    }else if ([withOption isEqualToString:@"Eraser"]) {
        red = 1.0; green = 1.0; blue = 1.0; width = 13.0;
    }else if ([withOption isEqualToString:@"Clear"]) {
        self.image = nil;
    }
}

- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event
{
    self.fingerMoved = NO;
    UITouch *touch = [touches anyObject];
    if ([touch tapCount] == 2) {
        self.image = nil;
        return;
    }

    self.lastPoint = [touch locationInView:self];
    self.lastPoint = CGPointMake(self.lastPoint.x, self.lastPoint.y - 20);
}

- (void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event
{
    self.fingerMoved = YES;
    UITouch *touch = [touches anyObject];
    CGPoint currentPoint = [touch locationInView:self];
    currentPoint.y -= 20;

    UIGraphicsBeginImageContext(self.frame.size);
    [self.image drawInRect:CGRectMake(0, 0, self.frame.size.width, self.frame.size.height)];
    CGContextSetLineCap(UIGraphicsGetCurrentContext(), kCGLineCapRound);
    CGContextSetLineWidth(UIGraphicsGetCurrentContext(), width);
    CGContextSetRGBStrokeColor(UIGraphicsGetCurrentContext(), red, green, blue, 1.0);
    CGContextMoveToPoint(UIGraphicsGetCurrentContext(), self.lastPoint.x, self.lastPoint.y);
    CGContextAddLineToPoint(UIGraphicsGetCurrentContext(), currentPoint.x, currentPoint.y);
    CGContextStrokePath(UIGraphicsGetCurrentContext());
    self.image = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();
    self.lastPoint = currentPoint;
}

- (void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event
{
    UITouch *touch = [touches anyObject];
    if ([touch tapCount] == 2) {
        self.image = nil;
        return;
    }

    if (!self.fingerMoved) {
        UIGraphicsBeginImageContext(self.frame.size);
        [self.image drawInRect:CGRectMake(0, 0, self.frame.size.width, self.frame.size.height)];
        CGContextSetLineCap(UIGraphicsGetCurrentContext(), kCGLineCapRound);
        CGContextSetLineWidth(UIGraphicsGetCurrentContext(), width);
        CGContextSetRGBStrokeColor(UIGraphicsGetCurrentContext(), red, green, blue, 1.0);
        CGContextMoveToPoint(UIGraphicsGetCurrentContext(), self.lastPoint.x, self.lastPoint.y);
        CGContextAddLineToPoint(UIGraphicsGetCurrentContext(), self.lastPoint.x, self.lastPoint.y);
        CGContextStrokePath(UIGraphicsGetCurrentContext());
        self.image = UIGraphicsGetImageFromCurrentImageContext();
        UIGraphicsEndImageContext();
    }
}

/*
// Only override drawRect: if you perform custom drawing.
// An empty implementation adversely affects performance during animation.
- (void)drawRect:(CGRect)rect
{
    // Drawing code
}
*/

@end

Answer 1

Silly mistake in some other code. Fixed now.