检查字典中是否有NULL 类型,如果有的话,转换成"",因为字典中又null ,是不能存入到NSUserDefalut 里面的.

//该方法是检查字典中是否有nil 的,有nil就转行成""

- (NSDictionary *)checkDict:(NSDictionary *)sender

{

NSMutableDictionary * dict_mutable = [[NSMutableDictionary alloc] init];

NSArray * keys = sender.allKeys;

for (NSString * key in keys) {

if ([[sender objectForKey:key] isKindOfClass:[NSDictionary class]]) {

NSDictionary * tempDict = [self checkDict:[sender objectForKey:key]];

[dict_mutable setObject:tempDict forKey:key];

}

else{

if ([[sender objectForKey:key] isKindOfClass:[[NSNull null] class]]) {

[dict_mutable setObject:@"" forKey:key];

}

else{

[dict_mutable setObject:[sender objectForKey:key] forKey:key];

}

}

}

return dict_mutable;

}