iOS : How to make a simple block? - ios

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;

Answer 1

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);
}
}

Answer 2

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.

Answer 3

Try https://github.com/lavoy/ALActionBlocks
It supports UIControl (UIButton), UIBarButtonItem, and UIGestureRecognizer. It is also supported using CocoaPods.

Answer 4

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();