CODEWITHSUNDEEP
iosobjective-cxcodeblock
Hesham
Hesham

Reputation: 5274

Xcode omitting parameters names of block

I have a block property that looks like this:

@property (nonatomic, copy) void (^indexChangeBlock)(NSInteger index);

When I try to set the value for this property, Xcode autocomplete will omit the parameter name leaving me with something like this:

[self.segmentedControl3 setIndexChangeBlock:^(NSInteger) {
    code
}];

Then Xcode shows a Parameter name omitted error. I'm aware that I can solve this by adding the parameter name manually to make it look like this:

[self.segmentedControl3 setIndexChangeBlock:^(NSInteger index) {
    code
}];

My questions is, how can I make Xcode add the parameters names automatically. Or in other words, prevent it from removing them.

Upvotes: 7

Views: 3993

Answers (2)

Alex Gray
Alex Gray

Reputation: 16463

In exacerbated frustration, I made a macro consolidating this gross process..

#define BlockProperty(SIGNATURE,TYPENAME,varname,Varname) typedef SIGNATURE; @property (nonatomic,copy) TYPENAME varname; - (void) set##Varname:(TYPENAME)_

Now what Previously would've required (for proper autocompletion)..

typedef void(^OnEvent)(BOOL ok,id result);
@property (nonatomic,copy) OnEvent varname;
- (void) setVarname:(OnEvent)_;

is simply 

BlockProperty(void(^OnEvent)(BOOL ok, id result),OnEvent,varname,VarName);

QUITE a bit easier, less verbose, AND you get the benefit of the typedef AND and you don't have to create the unsightly, theoretically unneeded setter declaration!

If you WANT to reuse a "type" you'll need another one (which this time will only take THREE parameters (as the block type cannot be redeclared).

#define BlockProp(TYPENAME,varname,Varname) @property (nonatomic,copy) TYPENAME varname; - (void)  set##Varname:(TYPENAME)_

BlockProp(OnEvent,anotherVar,AnotherVar);

You could just create a new block type (name) for each property even if their signatures match (using the first macro), but that's kind of gross. Enjoy!

Upvotes: 1

Jonathan Cichon
Jonathan Cichon

Reputation: 4406

possible solution:

typedef void (^IndexChangeBlock)(NSInteger index);

and define your property with

@property (nonatomic, copy) IndexChangeBlock indexChangeBlock;

and if you add

- (void)setIndexChangeBlock:(IndexChangeBlock)indexChangeBlock;

everything should work

Upvotes: 3

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