问题
I have a NSDictionary and i want to group it creating an array of objects by date
Example of the main NSDictionary:
({
date = "2014-04-27";
group = "yellow.png";
length = 180;
},
{
date = "2014-04-28";
group = "blue.png";
length = 180;
},
{
date = "2014-04-27";
group = "blue.png";
length = 120;
})
I want to group something similar as:
2014-04-27 = (
{
date = "2014-04-27";
group = "yellow.png";
length = 180;
},
{
date = "2014-04-27";
group = "blue.png";
length = 180;
})
2014-04-28 = ( {
date = "2014-04-28";
group = "blue.png";
length = 120;
})
Could someone help me? i have tried many FOR but i cant get it
回答1:
It appears as though your original data structure is an array of dictionaries. Was your question phrased incorrectly? I see each individual dictionary but they are not keyed on anything in the top level data structure.
Assuming that is the case (you have an array called originalArray
NSMutableDictionary *dictionaryByDate = [NSMutableDictionary new];
for(NSDictionary *dictionary in originalArray)
{
NSString *dateString = dictionary[@"date"];
NSMutableArray *arrayWithSameDate = dictionaryByDate[dateString];
if(! arrayWithSameDate)
{
arrayWithSameDate = [NSMutableArray new];
dictionaryByDate[dateString] = arrayWithSameDate;
}
[arrayWithSameDate addObject: dictionary];
}
By the end of this, dictionaryByDate will be a dictionary (keyed on date) of arrays (all objects in a given array will be dictionaries with the same date).
来源：https://stackoverflow.com/questions/22288481/group-nsdictionary-by-dates