Objective-C Blocks: Incompatible block pointer types

Question

I'm trying to implement a block call. Here is my method:

- (void) runTest; {
    void (^MyBlock)(id, NSUInteger, BOOL) = ^(id obj, NSUInteger idx, BOOL stop) {
        NSLog(@"Video game %@", (NSString *)obj);
    };

    BOOL stop;
    MyBlock(@"Path of exile", 0, &stop);

    NSArray *videoGames = @[@"fallout", @"Deus ex",@"final fintasy"];

    [videoGames enumerateObjectsUsingBlock:MyBlock];
}

But on this line:

[videoGames enumerateObjectsUsingBlock:MyBlock];

I'm getting this error:

Incompatible block pointer types sending 'void (^__strong)(__strong id, NSUInteger, BOOL)' to parameter of type 'void (^ _Nonnull)(id _Nonnull __strong, NSUInteger, BOOL * _Nonnull)'

Any of you knows what I'm doing wrong or how can I fix this?

I'll really appreciate your help.

Side note, if you know that the object will be a always a NSString, you can replace ^(id obj with ^(NSString * obj avoiding the next casting (NSString *)obj. — Larme
– Larme, Commented May 29, 2020 at 8:00

dRAGONAIR · Accepted Answer · 2020-05-29 03:22:09Z

2

the Bool parameter of the Block should be a pointer hence you need to add *

- (void) runTest; {
    void (^MyBlock)(id, NSUInteger, BOOL *) = ^(id obj, NSUInteger idx, BOOL *stop) {
        NSLog(@"Video game %@", (NSString *)obj);
    };

    BOOL stop;
    MyBlock(@"Path of exile", 0, &stop);

    NSArray *videoGames = @[@"fallout", @"Deus ex",@"final fintasy"];
   [videoGames enumerateObjectsUsingBlock:MyBlock];
}

answered May 29, 2020 at 3:22

dRAGONAIR

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Comments

pompopo · Accepted Answer · 2020-05-29 03:17:11Z

1

The 3rd parameter of MyBlock should be the pointer of BOOL.

So, add * like below

     void (^MyBlock)(id, NSUInteger, BOOL*) = ^(id obj, NSUInteger idx, BOOL *stop) {
         NSLog(@"Video game %@", (NSString *)obj);
     };

https://developer.apple.com/documentation/foundation/nsarray/1415846-enumerateobjectsusingblock?language=objc

(void)enumerateObjectsUsingBlock:(void (^)(ObjectType obj, NSUInteger idx, BOOL *stop))block;

answered May 29, 2020 at 3:17

pompopo

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