这个问题类似于
this question,但是这种方法只适用于字典的根级别.
我正在用空字符串替换任何NSNull值的发生,所以我可以将完整的字典保存到plist文件(如果我添加NSNull的文件将不会写入).
但是,我的字典里面有嵌套的字典.喜欢这个：
"dictKeyName" = {
innerStrKeyName = "This is a string in a dictionary";
innerNullKeyName = "<null>";
innerDictKeyName = {
"innerDictStrKeyName" = "This is a string in a Dictionary in another Dictionary";
"innerDictNullKeyName" = "<null>";
};
};
如果我使用：
@interface NSDictionary (JRAdditions)
- (NSDictionary *) dictionaryByReplacingNullsWithStrings;
@end
@implementation NSDictionary (JRAdditions)
- (NSDictionary *) dictionaryByReplacingNullsWithStrings {
const NSMutableDictionary *replaced = [NSMutableDictionary dictionaryWithDictionary:self];
const id nul = [NSNull null];
const Nsstring *blank = @"";
for(Nsstring *key in replaced) {
const id object = [self objectForKey:key];
if(object == nul) {
[replaced setobject:blank forKey:key];
}
}
return [NSDictionary dictionaryWithDictionary:replaced];
}
@end
我得到这样的东西：
"dictKeyName" = {
innerStrKeyName = "This is a string in a dictionary";
innerNullKeyName = ""; <-- this value has changed
innerDictKeyName = {
"innerDictStrKeyName" = "This is a string in a Dictionary in another Dictionary";
"innerDictNullKeyName" = "<null>"; <-- this value hasn't changed
};
};
有没有办法从所有字典中查找每个NSNull值,包括嵌套字典？？
编辑：
数据正在从JSON Feed中获取,因此我收到的数据是动态的(我不想每次更改Feed时都更新该应用).
解决方法
该方法的一个小修改可以使其递归：
@interface NSDictionary (JRAdditions)
- (NSDictionary *) dictionaryByReplacingNullsWithStrings;
@end
@implementation NSDictionary (JRAdditions)
- (NSDictionary *) dictionaryByReplacingNullsWithStrings {
const NSMutableDictionary *replaced = [NSMutableDictionary dictionaryWithDictionary: self];
const id nul = [NSNull null];
const Nsstring *blank = @"";
for (Nsstring *key in self) {
const id object = [self objectForKey: key];
if (object == nul) {
[replaced setobject: blank forKey: key];
}
else if ([object isKindOfClass: [NSDictionary class]]) {
[replaced setobject: [(NSDictionary *) object dictionaryByReplacingNullsWithStrings] forKey: key];
}
}
return [NSDictionary dictionaryWithDictionary: replaced];
}
请注意,快速枚举现在是自己,而不是替换
上面的代码,这个例子：
NSMutableDictionary *dic1 = [NSMutableDictionary dictionary]; [dic1 setobject: @"string 1" forKey: @"key1.1"]; [dic1 setobject: [NSNull null] forKey: @"key1.2"]; NSMutableDictionary *dic2 = [NSMutableDictionary dictionary]; [dic2 setobject: @"string 2" forKey: @"key2.1"]; [dic2 setobject: [NSNull null] forKey: @"key2.2"]; [dic1 setobject: dic2 forKey: @"key1.3"]; NSLog(@"%@",dic1); NSLog(@"%@",[dic1 dictionaryByReplacingNullsWithStrings]);
呈现此结果：
2012-09-01 08:30:16.210 Test[57731:c07] {
"key1.1" = "string 1";
"key1.2" = "<null>";
"key1.3" = {
"key2.1" = "string 2";
"key2.2" = "<null>";
};
}
2012-09-01 08:30:16.212 Test[57731:c07] {
"key1.1" = "string 1";
"key1.2" = "";
"key1.3" = {
"key2.1" = "string 2";
"key2.2" = "";
};