Let's take a look at how NSArray passes block parameters

Reprinted from: http://www.cnblogs.com/ihojin/p/block_params.html

Let's take a look at how NSArray passes block parameters

...
@interface NSArray (NSExtendedArray)
…

#if NS_BLOCKS_AVAILABLE
- (void)enumerateObjectsUsingBlock:(void (^)(id obj, NSUInteger idx, BOOL *stop))block NS_AVAILABLE(10_6, 4_0);

…
@end

For situations that do not require parameters, such as just want to call another method after the end of a method

//Realization-
(void)endInput:(void (^)())completion
{
    [UIView animateWithDuration:0.25 animations:^{

    } completion:^(BOOL finished) {

        if (completion) {
            completion();
        }
    }];
}

//Call
[instance endInput:^{
    //Do something
}];