添加NSArray中的所有值并找到平均值

Question

我正在使用以下内容获取输出:

    2013-06-06 11:44:27.325 [2570:907] Rating: 0
    2013-06-06 11:44:27.326 [2570:907] Rating: 2
    2013-06-06 11:44:27.327 [2570:907] Rating: 3 


[rateQuery findObjectsInBackgroundWithBlock:^(NSArray *rateObjects, NSError *error)
 {
     if( !error )
     {
         NSLog(@"rateobject %@", rateObjects);

         for (id item in rateObjects) {

             int ratingVal = [[item objectForKey:@"Rating"] intValue];
             NSLog(@"Rating: %d", ratingVal);
         }

     }
 }
 ];

我想添加数字以获得总数然后除以计数以获得平均"评级".

我试过这个,但显然语法不正确.我想我需要使用NSArray而不是"item":

NSNumber *sum=[[item objectForKey:@"Rating"] valueForKeyPath:@"@sum.floatValue"];
                 NSLog(@"Rating Sum: %@", sum);

谢谢你的帮助.

Answer 1

您可以使用KVC获得平均值.一个例子

NSArray *objects = @[
@{ @"Rating": @4 },
@{ @"Rating": @6 },
@{ @"Rating": @10 }
];

NSLog(@"Average: %@", [objects valueForKeyPath:@"@avg.Rating"]);
// results in "Average: 6.666666"

所以在你的情况下使用:

NSNumber *sum = [rateObjects valueForKeyPath:@"@sum.Rating"];
NSNumber *average = [rateObjects valueForKeyPath:@"@avg.Rating"];