replace a value in NSDictionary in iphone

问题:

I have a array(dataArray) of NSDictionary "item". It has datas like "david"for key "name" and "85" for key "marks" etc for 5 students.I want to replace the mark of david to 90 with respect to the array index value(ie 0 for dictionary containing david and 85).How can i do it.Please help me.

EDIT:

The code for content in array is

[item setobject:name forkey:@"Name"]; [item setobject:mark forkey:@"Marks"]; [dataArray addOject:item] 

The above code goes inside parsing, so i have array with 5 objetcs(students), their name and marks , now i want to replace the mark of the first object in the dataArray. Hope youcan understand the structure of my result.

回答1:

Here's what you can do:

NSMutableDictionary *newDict = [[NSMutableDictionary alloc] init]; NSDictionary *oldDict = (NSDictionary *)[dataArray objectAtIndex:0]; [newDict addEntriesFromDictionary:oldDict]; [newDict setObject:@"Don" forKey:@"Name"]; [dataArray replaceObjectAtIndex:0 withObject:newDict]; [newDict release]; 

Hope this helps!

回答2:

You first need an NSMutableDictionary with it you can change the key and value.

It would be like this:

NSMutableDictionary *dict = [NSMutableDictionary dictionaryWithObjectsAndKeys:@"david", @"name", "85", @"marks", nil];  [dict setObject:@"90" forKey:@"david"]; 

回答3:

If you want to update an object in a NSDictionary you should use NSMutableDictionary instead. NSMutableDictionary has the following EXTRA methods

Adding Entries

• setObject:forKey:
• setValue:forKey:
• addEntriesFromDictionary:
• setDictionary:

Removing Entries

• removeObjectForKey:
• removeAllObjects
• removeObjectsForKeys:

回答4:

 // NSDictionary *dict = ...     NSMutableDictionary *mutableDict = [dict mutableCopy];     [mutableDict setObject:@"myObject" forKey:@"myKey"];     dict = [mutableDict mutableCopy]; 

I hope it helps

回答5:

[davidsRecord setObject:@"100" forkey:@"mark"]; 

文章来源: replace a value in NSDictionary in iphone