How to Disable and Enable ScrollView on the touch

Question

I'm new in iOS and I'm facing problem for Sign on a view.

I've created a view of Sign.As Shown in Image.

But when I added the view in the ScrollView I'm not able to Sign on it.So my Question is how to disable the scrollview on the view touch. I've used a code same as in this link How to draw Signature on UIView answer given by user3182143.

Thanks in advance

Answer 1

You should not add all your controls like label or view or whatever directly on scrollview.

You should add first UIView on scrollview and on that UIView you should add your all labels or views like your signature view.

Second thing your constraint for your scrolview should be

top,bottom,leading,trailing

Constraints for UIVIew - view in scrollview - top,bottom,leading,trailing, fixed height and center x (horizontally in container) - this is for vertical scroll view if you want horizontal scrolview then two constraint should be different - fixed width and center y instead!

Then you should add your signature view or label on that view and you can set it's constraint like - top,leading,trailing,fixed height or as per your need!

So make sure that your setup match with the scenario that i have mentioned above!

Answer 2

You can implement UITapGestureRecognizer in your class and add action on your view to desable the scrollview.

let tap = UITapGestureRecognizer(target :self,action :"handleTap:")
tap.delegate = self
tap.numberOfTapsRequired = 1
yourView.addGestureRecognizer(tap)

Hope this helps.

Answer 3

I tried with answer what you ask here.

I set scroll inside the view.Then I tried to write on the view but I could not do that.After that I hidden the scroll. Now it works.

SignatureDrawView.h

#import <UIKit/UIKit.h>

@interface SignatureDrawView : UIView

@property (nonatomic, retain) UIGestureRecognizer *theSwipeGesture;
@property (nonatomic, retain) UIImageView *drawImage;
@property (nonatomic, assign) CGPoint lastPoint;
@property (nonatomic, assign) BOOL mouseSwiped;
@property (nonatomic, assign) NSInteger mouseMoved;




- (void)erase;
- (void)setSignature:(NSData *)theLastData;
- (BOOL)isSignatureWrite;

@end

SignatureDrawView.m

#import "SignatureDrawView.h"

@implementation SignatureDrawView

@synthesize theSwipeGesture;
@synthesize drawImage;
@synthesize lastPoint;
@synthesize mouseSwiped;
@synthesize mouseMoved;

#pragma mark - View lifecycle

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

- (id)initWithCoder:(NSCoder*)coder 
{
    if ((self = [super initWithCoder:coder]))
    {
      drawImage = [[UIImageView alloc] initWithImage:nil];
      drawImage.frame = CGRectMake(0, 0, self.frame.size.width, self.frame.size.height);
      [self addSubview:drawImage];
      self.backgroundColor = [UIColor whiteColor];
      mouseMoved = 0;


    }
    return self;
 }

 #pragma mark touch handling

- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event {
for (UITouch *touch in touches)
{
     NSArray *array = touch.gestureRecognizers;
     for (UIGestureRecognizer *gesture in array)
     {
        if (gesture.enabled & [gesture isMemberOfClass:[UISwipeGestureRecognizer class]])
        {
            gesture.enabled = NO;
            self.theSwipeGesture = gesture;
        }
      }
   }

   mouseSwiped = NO;
   UITouch *touch = [touches anyObject];

   lastPoint = [touch locationInView:self];

   [[NSNotificationCenter defaultCenter] postNotificationName:@"stopscroll" object:self];

}

- (void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event 
{
   mouseSwiped = YES;

   UITouch *touch = [touches anyObject];
   CGPoint currentPoint = [touch locationInView:self];

   UIGraphicsBeginImageContext(self.frame.size);
   [drawImage.image drawInRect:CGRectMake(0, 0, self.frame.size.width, self.frame.size.height)];
   CGContextSetLineCap(UIGraphicsGetCurrentContext(), kCGLineCapRound);
   CGContextSetLineWidth(UIGraphicsGetCurrentContext(), 3.0);
   CGContextSetRGBStrokeColor(UIGraphicsGetCurrentContext(), 0.0, 0.0, 0.0, 1.0);
   CGContextBeginPath(UIGraphicsGetCurrentContext());
   CGContextMoveToPoint(UIGraphicsGetCurrentContext(), lastPoint.x, lastPoint.y);
   CGContextAddLineToPoint(UIGraphicsGetCurrentContext(), currentPoint.x, currentPoint.y);
   CGContextStrokePath(UIGraphicsGetCurrentContext());
   drawImage.image = UIGraphicsGetImageFromCurrentImageContext();
   UIGraphicsEndImageContext();

   lastPoint = currentPoint;

   mouseMoved++;

   [[NSNotificationCenter defaultCenter] postNotificationName:@"stopscroll" object:self];


   if (mouseMoved == 10) {
    mouseMoved = 0;
    }
}

- (void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event
{
   if(!mouseSwiped)
   {
      UIGraphicsBeginImageContext(self.frame.size);
      [drawImage.image drawInRect:CGRectMake(0, 0, self.frame.size.width, self.frame.size.height)];
      CGContextSetLineCap(UIGraphicsGetCurrentContext(), kCGLineCapRound);
      CGContextSetLineWidth(UIGraphicsGetCurrentContext(), 3.0);
      CGContextSetRGBStrokeColor(UIGraphicsGetCurrentContext(), 0.0, 0.0, 0.0, 1.0);
      CGContextMoveToPoint(UIGraphicsGetCurrentContext(), lastPoint.x, lastPoint.y);
      CGContextAddLineToPoint(UIGraphicsGetCurrentContext(), lastPoint.x, lastPoint.y);
      CGContextStrokePath(UIGraphicsGetCurrentContext());
      CGContextFlush(UIGraphicsGetCurrentContext());
      drawImage.image = UIGraphicsGetImageFromCurrentImageContext();
      UIGraphicsEndImageContext();
     }
    self.theSwipeGesture.enabled = YES;
    mouseSwiped = YES;
    [[NSNotificationCenter defaultCenter] postNotificationName:@"stopscroll" object:self];

 }

#pragma mark Methods

- (void)erase
{
   mouseSwiped = NO;
   drawImage.image = nil;
}

- (void)setSignature:(NSData *)theLastData
{
    UIImage *image = [UIImage imageWithData:theLastData];
    if (image != nil) 
    {
      drawImage.image = [UIImage imageWithData:theLastData];
      mouseSwiped = YES;
    }
 }

 - (BOOL)isSignatureWrite
 {
   return mouseSwiped;
 }

 @end

What I added in above is just I created the post notification for stop the scroll when I touch to signature on view.It is implemented in start,moving and end method.

[[NSNotificationCenter defaultCenter] postNotificationName:@"stopscroll" object:self];

SignatureDrawView.m

Next in ViewController I created the scrollView and UIImageView with UIView.

ViewController.h

#import <UIKit/UIKit.h>
#import "SignatureDrawView.h"

@interface ViewController : UIViewController

@property (strong, nonatomic) IBOutlet UIScrollView *scroll;

@property (strong, nonatomic) IBOutlet SignatureDrawView *drawSignView;

@property (strong, nonatomic) IBOutlet UITextField *txtFldDesc;

- (IBAction)actionSave:(id)sender;

- (IBAction)actionClear:(id)sender;

@end

ViewController.m

#import "ViewController.h"

@interface ViewController ()

@end

@implementation ViewController

@synthesize drawSignView,scroll,txtFldDesc;

- (void)viewDidLoad 
{
  [super viewDidLoad];
// Do any additional setup after loading the view, typically from a nib.
   scroll.contentSize = CGSizeMake(self.view.frame.size.width, self.view.frame.size.height+200);
   [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(stopScroll:) name:@"stopscroll" object:nil];
}

- (void)stopScroll:(NSNotification *)notification
{
    if([[notification name] isEqualToString:@"stopscroll"])
        scroll.scrollEnabled = NO;
}

- (void)didReceiveMemoryWarning {
[super didReceiveMemoryWarning];
// Dispose of any resources that can be recreated.
}

- (IBAction)actionSave:(id)sender 
{
    scroll.scrollEnabled = YES;
   // code for save the signature
    UIGraphicsBeginImageContext(self.drawSignView.bounds.size); 
    [[self.drawSignView.layer presentationLayer] renderInContext:UIGraphicsGetCurrentContext()];
    UIImage *viewImage = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();
    NSData *postData = UIImageJPEGRepresentation(viewImage, 1.0);
    ....Then do your stuff to save this in DB or server
}
- (IBAction)actionClear:(id)sender 
{
    scroll.scrollEnabled = YES;
    //code for clear the signature
    [self.drawSignView erase];
}
@end

In above viewDidLoad method I added addObserver for stop scrolling.

[[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(stopScroll:) name:@"stopscroll" object:nil];

Finally I implemented the stopScroll: method

Also I set the scroll.scrollEnabled = YES in actionSave and actionclear method

I gave you the solution only after I tried and worked out well.

Check and apply my code.It works fine and perfectly now.

Output Result