How to check if an NSDictionary or NSMutableDictionary contains a key?

Question

I need to check if an dict has a key or not. How?

Answer 1

Yes. This kind of errors are very common and lead to app crash. So I use to add NSDictionary in each project as below:

//.h file code :

@interface NSDictionary (AppDictionary)

- (id)objectForKeyNotNull : (id)key;

@end

//.m file code is as below

#import "NSDictionary+WKDictionary.h"

@implementation NSDictionary (WKDictionary)

 - (id)objectForKeyNotNull:(id)key {

    id object = [self objectForKey:key];
    if (object == [NSNull null])
     return nil;

    return object;
 }

@end

In code you can use as below:

NSStrting *testString = [dict objectForKeyNotNull:@"blah"];