iOS : How to make a simple block?

Question

I've a custom view subclass with UIView, in it, I've two buttons with an action, now I want to learn something good, and I don't want to implement a delegate to know which button tapped from other class.

I'm showing my custom view with this method,

CustomView *view = [[CustomView alloc] init];
[view show];

This will show my custom view, with two buttons inside (please assume everything is working fine, I only want to implement block to know which button have been tapped). ^_^

What I've tried for block,

- (void) showViewWithCompletionBlock:(void(^)(CustomViewType type))completion;

and yes, I would able to write like this,

CustomView *view = [[CustomView alloc] init];
[view showViewWithCompletionBlock:^(CustomViewType type) {

}];

but now here's the trouble, I don't know how to call this block (or how I can return CustomViewType) when button tap?

Those two buttons action is like this,

- (void) someAction:(UIButton *)sender {
     //sender.tag is a CustomViewType which user choose
}

For a note, CustomViewType is an enum like this,

typedef enum {
    CustomViewTypeOption1,
    CustomViewTypeOption2,
}CustomViewType;

trojanfoe · Accepted Answer · 2014-11-03 10:26:12Z

It's easier to deal with blocks using a typedef:

typedef void(^CustomViewCompletionBlock)(CustomViewType type);

(same thing goes for function pointers).

Now store this block in the custom view, using a private category in the .m file:

@interface CustomView () {
    CustomViewCompletionBlock _completionBlock;
}
@end

@implementation CustomView
...
@end

Do whatever is necessary to display the view and store the completion block:

- (void)showViewWithCompletionBlock:(CustomViewCompletionBlock)completion
{
    // Do whatever it takes to "display" the view
    ...
    _completionBlock = completion;
}

and then call the completion block as-and-when:

- (IBAction)button1Action:(id)sender
{
    // Whatever else this method does
    ...
    if (_completionBlock) {
        _completionBlock(CustomViewTypeOption1);
    }
}

- (IBAction)button2Action:(id)sender
{
    // Whatever else this method does
    ...
    if (_completionBlock) {
        _completionBlock(CustomViewTypeOption2);
    }
}

ChintaN -Maddy- Ramani · Accepted Answer · 2014-11-03 10:25:37Z

Please try below code. when you call compilation . take reference of that compilation and when you want to call that block just use that reference.

in .h

typedef enum {
CustomViewTypeOption1,
CustomViewTypeOption2,
}CustomViewType;

typedef void(^CustomViewCompletionBlock)(CustomViewType type);

@interface CustomView : UIView
{
    CustomViewCompletionBlock custVTypeBlock;
}
- (void)showViewWithCompletionBlock:(CustomViewCompletionBlock)completion;

@end

in .m

- (void)showViewWithCompletionBlock:(CustomViewCompletionBlock)completion
{
    custVTypeBlock = completion;
    //i'm calling this for sample.
    dispatch_after(dispatch_time(DISPATCH_TIME_NOW, (int64_t)(3 * NSEC_PER_SEC)), dispatch_get_main_queue(), ^{
        [self someAction:nil];
    });
}
- (void) someAction:(UIButton *)sender {
    //sender.tag is a CustomViewType which user choose
    // call your compilation with your enum.
    if(custVTypeBlock)
        custVTypeBlock(0);
}

Maybe this will help you.

Jay Gajjar · Accepted Answer · 2014-11-03 10:09:40Z

0

Try https://github.com/lavoy/ALActionBlocks

It supports UIControl (UIButton), UIBarButtonItem, and UIGestureRecognizer. It is also supported using CocoaPods.

answered Nov 3, 2014 at 10:09

Jay Gajjar

2,7813 gold badges23 silver badges36 bronze badges

Comments

avismara · Accepted Answer · 2014-11-03 10:13:02Z

0

Calling a block type is just like calling a C method. If you your block variable name is, say, myBlock and if it returns a CustomType, then this will work for you:

CustomType blockReturnedCustomType = myBlock();

answered Nov 3, 2014 at 10:13

avismara

5,1592 gold badges36 silver badges58 bronze badges

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