CODEWITHSUNDEEP
objective-creactive-cocoa
Alex
Alex

Reputation: 8991

Enable button according to NSSet object count using ReactiveCocoa

I'm trying to use ReactiveCocoa to enable a button depending on if the number of objects in an NSMutableSet instance is greater than zero.

I am using the following code, but am experiencing a crash at runtime. Any ideas?

RAC(self.navigationItem.leftBarButtonItem, enabled) = [RACSignal combineLatest:@[self.selectedRows] reduce:^(NSMutableSet *set){
    return @([set count] > 0);
}];

'NSInvalidArgumentException', reason: '-[__NSSetM map:]: unrecognized selector sent to instance 0x9671d10'

Upvotes: 1

Views: 1582

Answers (2)

geekay
geekay

Reputation: 1673

Thats sad to know that NSarry, NSMutableArray do not support KVO. While doing something similar

But thankfully, UIViewController is KVO compliant. 

//create a readonly property selectionCount
@property (nonatomic, readonly)NSInteger selectionCount;
...

//Implement the getter method
-(NSInteger)selectionCount{
    return self.arrSelection.count;
}
...

RAC(self.btnConfirm, enabled) = [RACSignal combineLatest:@[RACAbleWithStart(self.selectionCount)] reduce:^(NSNumber *count){
        return @([count integerValue] > 0);
    }];

Upvotes: 0

Ash Furrow
Ash Furrow

Reputation: 12421

You need to turn your selectedRows property into a signal:

RAC(self.navigationItem.leftBarButtonItem, enabled) = [RACSignal combineLatest:@[RACAbleWithStart(self.selectedRows)] reduce:^(NSMutableSet *set){
    return @([set count] > 0);
}];

Upvotes: 1

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