short cut technique for finding null value from Dictionary? - ios

Question

I have 100 key and value in nsmutabledictornary and i want to check that any value have null or not. Do you have any short function or technique?
I don't want to multiple line code like check every key and value. Your answer would be appreciated.

Answer 1

This code will give you the set of keys which have (non)null values. You can't store actual nil values in a dictionary, so [NSNull null] is assumed. The predicate is trivially alterable to any other condition.
NSDictionary *d = #{ #"a" : #"1", #"b" : [NSNull null] };
NSSet *nullKeys = [d keysOfEntriesPassingTest:^BOOL(NSString *key, id obj, BOOL *stop) {
return [d[key] isKindOfClass:[NSNull class]];
}];
NSSet *nonnullKeys = [d keysOfEntriesPassingTest:^BOOL(NSString *key, id obj, BOOL *stop) {
return [d[key] isKindOfClass:[NSNull class]] == NO;
}];
From here, you can use the keys to generate a corresponding dictionary, if needed.
NSMutableDictionary *nonNullDict = [NSMutableDictionary dictionary];
[d enumerateKeysAndObjectsUsingBlock:^(NSString *key, id obj, BOOL *stop) {
if ([nonnullKeys contains:key]) {
nonNullDict[key] = obj;
}
}];
If you don't need a separate list of keys, and just need the filtered dictionary, skip the first step and modify the second part to read as follows:
NSMutableDictionary *nonNullDict = [NSMutableDictionary dictionary];
[d enumerateKeysAndObjectsUsingBlock:^(NSString *key, id obj, BOOL *stop) {
if ([obj isKindOfClass:[NSNull null]] == NO) {
nonNullDict[key] = obj;
}
}];

Answer 2

Write category on NSDictionary it will provide you null free dictionary. Here is the category I have written for myself.
code for .h file (interface)
#import <Foundation/Foundation.h>
#interface NSDictionary (CheckNull)
{
}
- (NSDictionary *)nullFreeDictionary;
#end
Code for .m file. (implementation)
#import "NSDictionary+CheckNull.h"
#implementation NSDictionary (CheckNull)
- (NSDictionary *) nullFreeDictionary
{
NSMutableDictionary *tempDictionary = [self mutableCopy];
for (NSString *key in tempDictionary.allKeys) {
NSString *value = [tempDictionary valueForKey:key];
if ([value isKindOfClass:[NSString class]]) {
if (value == (id)[NSNull null] || value == nil || value.length == 0) {
[tempDictionary setValue:#"" forKey:key];
}
}
}
return tempDictionary;
}
Call null free method on your dictionary using above category.
NSDictionary *dict = [dict nullFreeDictionary];

Answer 3

//To remove NULL from Dictionary
-(NSMutableDictionary *)removeNullFromDictionary : (NSMutableDictionary *)dict
{
// if (![dict isKindOfClass:[NSMutableDictionary class]])
// {
// }
dict = [[NSMutableDictionary alloc] initWithDictionary:dict];
for (NSString * key in [dict allKeys])
{
if ([dict[key] isKindOfClass:[NSNull class]])
{
[dict setValue:#"" forKey:key];
}
else if ([dict[key] isKindOfClass:[NSMutableDictionary class]]||[dict[key] isKindOfClass:[NSDictionary class]])
{
dict[key] = [self removeNullFromDictionary:[NSMutableDictionary dictionaryWithDictionary:dict[key]]];
}
else if ([dict[key] isKindOfClass:[NSMutableArray class]]||[dict[key] isKindOfClass:[NSArray class]])
{
dict[key] = [self removeNullFromArray:[NSMutableArray arrayWithArray:dict[key]]];
}
}
return dict;
}
//To remove NULL from Array
-(NSMutableArray *)removeNullFromArray : (NSMutableArray *)arr
{
// if (![arr respondsToSelector:#selector(addObject:)])
// {
// arr = [[NSMutableArray alloc] initWithArray:arr];
// }
arr = [[NSMutableArray alloc] initWithArray:arr];
for (int cnt = 0; cnt<[arr count]; cnt++)
{
if ([arr[cnt] isKindOfClass:[NSNull class]])
{
arr[cnt] = #"";
}
else if ([arr[cnt] isKindOfClass:[NSMutableDictionary class]]||[arr[cnt] isKindOfClass:[NSDictionary class]])
{
arr[cnt] = [self removeNullFromDictionary:[NSMutableDictionary dictionaryWithDictionary:arr[cnt]]];
}
else if ([arr[cnt] isKindOfClass:[NSMutableArray class]]||[arr[cnt] isKindOfClass:[NSArray class]])
{
arr[cnt] = [self removeNullFromArray:[NSMutableArray arrayWithArray:arr[cnt]]];
}
}
return arr;
}