ios - Method that returns block -

i wrote method can used dot notation, using block tricks

- (raginidbquery *(^)(id object))where;

this method can called using dot notation since doesn't receive parameters, (it does, using block returned)

so can call so:

query.where(object)

what need instead getting id object want receive in method:

- (nsenumerator *)where:(bool (^)(id object))predicate;

this method can called so:

[object where:^(id a){return [a intvalue]%2 == 1}];

what want combine both, calling method where using dot notation, sending predicate block in example above, tried :

- (raginidbquery *(^)(bool (^)(id object))where;

but gives me errors, question this:

how can declare block, takes block?

edit:

for looking answer check below, here tl;dr

- (raginidbquery *(^)(bool(^filterblock)(id object)))where;

first of all, you're doing bad thing. should treat difficulty evidence it's misguided goal. objective-c isn't c# or java or swift. it's objective-c. if want use dot notation call functions on ios, use swift. don't try hammer objective-c other language's mold.

second, use typedefs.

#import <foundation/foundation.h>  typedef bool (^myobject_wherepredicate)(id object); typedef nsenumerator *(^myobject_wherereturn)(myobject_wherepredicate);  @interface myobject: nsobject  - (myobject_wherereturn)where;  @end  @implementation myobject  - (myobject_wherereturn)where {     return ^(myobject_wherepredicate predicate) {         nsarray *array = @[ @"hello", @"world", @"this", @"is", @"a", @"test" ];         nspredicate *p = [nspredicate predicatewithblock:^bool(id evaluatedobject, nsdictionary *bindings) {             return predicate(evaluatedobject);         }];         return [array filteredarrayusingpredicate:p].objectenumerator;     }; }  @end  int main(int argc, const char * argv[]) {     @autoreleasepool {         myobject *it = [[myobject alloc] init];         nsenumerator *e = it.where(^(id object){             nsstring *string = object;             return [string containsstring:@"s"];         });         (nsstring *item in e) {             nslog(@"%@", item);         }     }     return 0; } 

output:

2015-05-31 12:34:31.191 commandline[1881:82976] 2015-05-31 12:34:31.192 commandline[1881:82976] 2015-05-31 12:34:31.192 commandline[1881:82976] test