when using @weakify get error unexpected '@' in the program

Question

When using @weakify, I get error unexpected '@' in the program. Am I missing some .h files? I already imported ReactiveCocoa.h. Is there any thing I should do ?

- (id)initWithFrame:(CGRect)frame
{
    self = [super initWithFrame:frame];
    if (self) {
        // Initialization code
        _isSeperateFill = YES;
        _isBorderStroke = NO;
        _isSeperatedStroke = YES;

        _contentWidth = 0;

        @weakify(self);
        [RACObserve(self, dataVO) subscribeNext:^(TableDataVO* dataVO){
            if( dataVO ){
                NSString* indexKey = [[dataVO.tableDataDictionary allKeys] objectAtIndex:0];

                _keys = [dataVO.tableDataDictionary allKeys];
                @strongify(self);
                _rows = [[self.dataVO.tableDataDictionary objectForKey:indexKey] count];
                @strongify(self);
                [self.styleVO setTableHeaderLineHorizontalMargin:self.styleVO.tableWidth / [_keys count]];
            }
        }];

        @weakify(self);
        [RACObserve(self, styleVO) subscribeNext:^(TableStyleVO* styleVO){
            if( styleVO ){
                styleVO.tableHeaderLineHorizontalMargin = styleVO.tableWidth / [_keys count] / 2;
            }
        }];

    }
    return self;
}

Are you importing `ReactiveCocoa.h` into the file where you’re trying to use `@weakify` (or into your .pch)? — Zev Eisenberg, Aug 14 '14 at 14:09
Yes, I imported the ReactiveCocoa.h and I can use RAC and RACObserve macros — benoitcn, Aug 15 '14 at 00:43
Can you post the lines that come before `@weakify`? Sometimes an error on one line is actually a mistake on the line before. — Zev Eisenberg, Aug 15 '14 at 00:51
snapshot url https://cloud.githubusercontent.com/assets/1966791/3929043/176300a0-2417-11e4-9e87-6ccabc8b4227.png — benoitcn, Aug 15 '14 at 01:01

Rob Bajorek · Accepted Answer · 2016-02-23T15:02:28.820

5

@weakify, @strongify and friends are part of libextobjc, not ReactiveCocoa proper.

Try adding this line (per @chakming's comment):

#import "ReactiveCocoa/RACEXTScope.h"

Or for pre-2.3.1 ReactiveCocoa (my original answer), use:

#import <ReactiveCocoa/EXTScope.h>

edited Feb 23 '16 at 15:02

answered Aug 15 '14 at 01:02

Rob Bajorek

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Yes, you are right. I missed to import that .h file – benoitcn Aug 15 '14 at 01:05
5

for reactivecocoa 2.3.1, it should be `#import "ReactiveCocoa/RACEXTScope.h"` – chakming Aug 15 '14 at 01:44

score 1 · Answer 2 · answered Jan 05 '15 at 21:06

Not strictly related to the question at hand, but I thought I'd comment and mention that your use and placement of weakify and strongify is incorrect. The correct version would be...

- (id)initWithFrame:(CGRect)frame
{
    self = [super initWithFrame:frame];
    if (self) {
        // Initialization code
        _isSeperateFill = YES;
        _isBorderStroke = NO;
        _isSeperatedStroke = YES;

        _contentWidth = 0;

        @weakify(self);
        [RACObserve(self, dataVO) subscribeNext:^(TableDataVO* dataVO){
            @strongify(self);
            if( dataVO ){
                NSString* indexKey = [[dataVO.tableDataDictionary allKeys] objectAtIndex:0];
                _keys = [dataVO.tableDataDictionary allKeys];
                _rows = [[self.dataVO.tableDataDictionary objectForKey:indexKey] count];
                [self.styleVO setTableHeaderLineHorizontalMargin:self.styleVO.tableWidth / [_keys count]];
            }
        }];

        [RACObserve(self, styleVO) subscribeNext:^(TableStyleVO* styleVO){
            if( styleVO ){
                styleVO.tableHeaderLineHorizontalMargin = styleVO.tableWidth / [_keys count] / 2;
            }
        }];

    }
    return self;
}

As you can see above, you only need to use weakify once. Once defined it's defined for the entire scope.

Similarly, strongify is only needed once in a block. Further, it's needed at the top of the block so you recapture the weak reference as a strong reference as soon as possible.

By the time it's used in your example it's possible that the captured weak reference to self could have gone out of scope.

when using @weakify get error unexpected '@' in the program

2 Answers2