如何检查值 null 并在 NSDictionary 中替换它 [英] How to check value null and replace it in NSDictionary
问题描述
现在，我正在使用 NSUserDefault 和 NSDictionary，我将 NSDictionary 保存在 NSUserDefault 中，不幸的是我不能，因为 NSDictionary 返回到 Json 具有空值.
Now, i'm working with the NSUserDefault and the NSDictionary, i save the NSDictionary in NSUserDefault, unfortunately i can't, because NSDictionary return to Json has null value.
我需要检查 NSDictionary 是否有空值并替换.怎么样?
I need check if NSDictionary has null value and replace. How?
这是 NSDictionary，
It's NSDictionary,
({
ID:11,
name:21-12-2012,
des:"<null>",
url:
[
{
ID:1,
name: "<null>"
},
{
ID:2,
name:"<null>"
}
]
},
{
ID:12,
name:if i die young,
des:"<null>",
url:
[
{
ID:3,
name: "<null>"
},
{
ID:21,
name:"<null>"
}
]
})
推荐答案
能否请您查看此链接，我想，它会对您有所帮助，谢谢您的链接替换嵌套 NSDictionary 中出现的 NSNull
could you please check this link, I think, it will be helpful to you, thanks for this link Replace occurrences of NSNull in nested NSDictionary
UPDATE:我稍微修改了一下原文，并使用了一些从这个链接将 nsarray 转换为 nsdictionary 的功能 将 NSArray 转换为 NSDictionary，因为我对您的代码一无所知，所以我尝试使我的 json 字符串尽可能接近您的字符串，并且它的工作，请参阅以下内容.:)
UPDATE: I modified original a bit, and use some the function of converting nsarray to nsdictionary from this link Convert NSArray to NSDictionary, cuz I don't know anything about your code, so I try to make my json string as close as possible to be the same as yours, and it's work, see the following. :)
- (void)viewDidLoad
{
[super viewDidLoad];
// Do any additional setup after loading the view, typically from a nib.
tmpDict = [[NSMutableDictionary alloc] init];
NSMutableDictionary *testDict = [[NSMutableDictionary alloc] init];
[testDict setValue:[NSNull null] forKey:@"NullValue"];
[testDict setValue:@"test" forKey:@"UnNull"];
subArr = [[NSMutableArray alloc] initWithObjects:testDict, testDict, nil];
[tmpDict setValue:[NSNull null] forKey:@"NullHere"];
[tmpDict setValue:@"wear" forKey:@"NotNull"];
[tmpDict setObject:subArr forKey:@"Array"];
myArr = [[NSMutableArray alloc] initWithObjects:tmpDict, tmpDict, nil];
NSLog(@"struct: %@", myArr);
[self dictionaryByReplacingNullsWithStrings];
}
- (void)didReceiveMemoryWarning
{
[super didReceiveMemoryWarning];
// Dispose of any resources that can be recreated.
}
- (void) dictionaryByReplacingNullsWithStrings {
const NSMutableDictionary *replaced = [NSMutableDictionary dictionaryWithDictionary: [self indexKeyedDictionaryFromArray:myArr]];
const id nul = [NSNull null];
const NSString *blank = @"";
for (NSString *key in [replaced allKeys]) {
const id object = [replaced objectForKey: key];
if (object == nul) {
[replaced setObject: blank forKey: key];
}
else if ([object isKindOfClass: [NSDictionary class]]) {
NSLog(@"found null inside and key is %@", key);
[replaced setObject:[self replaceNullInNested:object] forKey:key];
}
}
NSLog(@"replaced: %@", replaced);
}
- (NSMutableDictionary *)replaceNullInNested:(NSDictionary *)targetDict
{
//make it to be NSMutableDictionary in case that it is nsdictionary
NSMutableDictionary *m = [targetDict mutableCopy];
NSMutableDictionary *replaced = [NSMutableDictionary dictionaryWithDictionary: m];
const id nul = [NSNull null];
const NSString *blank = @"";
for (NSString *key in [replaced allKeys]) {
const id object = [replaced objectForKey: key];
if (object == nul) {
[replaced setObject: blank forKey: key];
}
else if ([object isKindOfClass: [NSArray class]]) {
NSLog(@"found null inside and key is %@", key);
//make it to be able to set value by create a new one
NSMutableArray *a = [object mutableCopy];
for (int i =0; i< [a count]; i++) {
for (NSString *subKey in [[a objectAtIndex:i] allKeys]) {
// NSLog(@"key: %@", subKey);
// NSLog(@"value: %@", [[object objectAtIndex:i] valueForKey:subKey]);
if ([[object objectAtIndex:i] valueForKey:subKey] == nul) {
[[object objectAtIndex:i] setValue:blank forKey:subKey];
}
}
}
//replace the updated one with old one
[replaced setObject:a forKey:key];
}
}
return replaced;
}
- (NSDictionary *) indexKeyedDictionaryFromArray:(NSArray *)array
{
id objectInstance;
NSUInteger indexKey = 0;
NSMutableDictionary *mutableDictionary = [[NSMutableDictionary alloc] init];
for (objectInstance in array)
[mutableDictionary setObject:objectInstance forKey:[NSNumber numberWithUnsignedInt:indexKey++]];
return (NSDictionary *)mutableDictionary;
}
从上面的代码，这是结果:
from the code above, this is the result:
replacenullvalue[1590:11303] struct: (
{
Array = (
{
NullValue = "<null>";
UnNull = test;
},
{
NullValue = "<null>";
UnNull = test;
}
);
NotNull = wear;
NullHere = "<null>";
},
{
Array = (
{
NullValue = "<null>";
UnNull = test;
},
{
NullValue = "<null>";
UnNull = test;
}
);
NotNull = wear;
NullHere = "<null>";
}
)
2012-12-16 15:16:22.790 replacenullvalue[1590:11303] found null inside and key is 0
2012-12-16 15:16:22.790 replacenullvalue[1590:11303] found null inside and key is Array
2012-12-16 15:16:22.791 replacenullvalue[1590:11303] found null inside and key is 1
2012-12-16 15:16:22.791 replacenullvalue[1590:11303] found null inside and key is Array
2012-12-16 15:16:22.792 replacenullvalue[1590:11303] replaced: {
0 = {
Array = (
{
NullValue = "";
UnNull = test;
},
{
NullValue = "";
UnNull = test;
}
);
NotNull = wear;
NullHere = "";
};
1 = {
Array = (
{
NullValue = "";
UnNull = test;
},
{
NullValue = "";
UnNull = test;
}
);
NotNull = wear;
NullHere = "";
};
}
希望对你有帮助:)
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