Trying to get the sum of a property in an array - ios

Question

I have an NSArray of objects and the data looks like this. I am currently trying to sum up the value of hours in the timeSheets property of the task given. I currently have a double for loop that does the job for the iPhone however it runs into a performance issue with lag on a UITableView on the iPad version. The code for the double for loop is at the bottom. I'm trying to use a mixture of NSExpressions and NSPredicates however, I cant seem to get these to add correctly.
<Tasks: 0xc563950> (entity: Tasks; id: 0xc561940 <x-coredata://36042CA3-F392-46FB-AF23-F0C396CE0989/Tasks/p8> ; data: {
assigneeID = 20;
budgetedHours = 5;
chargeNumber = 0;
completedProgress = 0;
createdBy = "Tyler Baetz";
dateCreated = "2013-09-06 19:18:40 +0000";
dateModified = "2013-09-11 04:53:32 +0000";
descriptions = nil;
dueDate = "2013-09-11 07:00:00 +0000";
modifiedBy = "Jose Alvarez";
name = Denver;
ownerID = 120;
parentID = 1914;
project = "0xc566070 <x-coredata://36042CA3-F392-46FB-AF23-F0C396CE0989/Projects/p2>";
projectID = 500910;
taskID = 1916;
taskPriority = nil;
taskPriorityID = 1;
taskStatus = nil;
taskStatusID = 3;
taskType = nil;
taskTypeID = 4;
tasks = "<relationship fault: 0xb4e9db0 'tasks'>";
timeSheets = (
"0xc553780 <x-coredata://36042CA3-F392-46FB-AF23-F0C396CE0989/TimeSheets/p12>",
"0xc5537a0 <x-coredata://36042CA3-F392-46FB-AF23-F0C396CE0989/TimeSheets/p14>",
"0xc5537b0 <x-coredata://36042CA3-F392-46FB-AF23-F0C396CE0989/TimeSheets/p15>"
);
}) with objects {(
<TimeSheets: 0xc555420> (entity: TimeSheets; id: 0xc553780 <x-coredata://36042CA3-F392-46FB-AF23-F0C396CE0989/TimeSheets/p12> ; data: {
approvedBy = nil;
comments = nil;
dateApproved = nil;
dateEntered = "2013-09-06 20:31:31 +0000";
employee = nil;
employeeID = 20;
enteredBy = 20;
hours = 173;
reportPeriod = nil;
reportPeriodID = 4;
task = "0xc561940 <x-coredata://36042CA3-F392-46FB-AF23-F0C396CE0989/Tasks/p8>";
taskID = 1916;
timeSheetDate = "2013-09-01 07:00:00 +0000";
timeSheetID = 1934;
timeStatus = nil;
timeStatusID = 1;
timeType = nil;
timeTypeID = 35;
}),
<TimeSheets: 0xc555730> (entity: TimeSheets; id: 0xc5537a0 <x-coredata://36042CA3-F392-46FB-AF23-F0C396CE0989/TimeSheets/p14> ; data: {
approvedBy = nil;
comments = "Friday :45";
dateApproved = nil;
dateEntered = "2013-09-06 20:31:31 +0000";
employee = nil;
employeeID = 20;
enteredBy = 20;
hours = 45;
reportPeriod = nil;
reportPeriodID = 4;
task = "0xc561940 <x-coredata://36042CA3-F392-46FB-AF23-F0C396CE0989/Tasks/p8>";
taskID = 1916;
timeSheetDate = "2013-09-06 07:00:00 +0000";
timeSheetID = 1937;
timeStatus = nil;
timeStatusID = 1;
timeType = nil;
timeTypeID = 35;
}),
<TimeSheets: 0xc5557a0> (entity: TimeSheets; id: 0xc5537b0 <x-coredata://36042CA3-F392-46FB-AF23-F0C396CE0989/TimeSheets/p15> ; data: {
approvedBy = nil;
comments = "Hello Man";
dateApproved = nil;
dateEntered = "2013-09-11 13:20:19 +0000";
employee = nil;
employeeID = 20;
enteredBy = 50;
hours = 300;
reportPeriod = nil;
reportPeriodID = 4;
task = "0xc561940 <x-coredata://36042CA3-F392-46FB-AF23-F0C396CE0989/Tasks/p8>";
taskID = 1916;
timeSheetDate = "2013-09-05 07:00:00 +0000";
timeSheetID = 2357;
timeStatus = nil;
timeStatusID = 1;
timeType = nil;
timeTypeID = 35;
})
)},
Relationship 'timeSheets' on managed object (0xc5639f0) <Tasks: 0xc5639f0> (entity: Tasks; id: 0xc561950 <x-coredata://36042CA3-F392-46FB-AF23-F0C396CE0989/Tasks/p9> ; data: {
assigneeID = 20;
budgetedHours = 3;
chargeNumber = 0;
completedProgress = 0;
createdBy = "Tyler Baetz";
dateCreated = "2013-09-06 19:17:01 +0000";
dateModified = "2013-09-12 18:34:55 +0000";
descriptions = nil;
dueDate = "2013-09-09 07:00:00 +0000";
modifiedBy = "Jose Alvarez";
name = "Jose's Task";
ownerID = 120;
parentID = 1913;
project = "0xc566070 <x-coredata://36042CA3-F392-46FB-AF23-F0C396CE0989/Projects/p2>";
projectID = 500910;
taskID = 1915;
taskPriority = nil;
taskPriorityID = 4;
taskStatus = nil;
taskStatusID = 3;
taskType = nil;
taskTypeID = 4;
tasks = "<relationship fault: 0xb4ee0d0 'tasks'>";
timeSheets = (
"0xc5537c0 <x-coredata://36042CA3-F392-46FB-AF23-F0C396CE0989/TimeSheets/p16>",
"0xc553810 <x-coredata://36042CA3-F392-46FB-AF23-F0C396CE0989/TimeSheets/p21>",
"0xc553800 <x-coredata://36042CA3-F392-46FB-AF23-F0C396CE0989/TimeSheets/p20>",
"0xc553790 <x-coredata://36042CA3-F392-46FB-AF23-F0C396CE0989/TimeSheets/p13>",
"0xc5537d0 <x-coredata://36042CA3-F392-46FB-AF23-F0C396CE0989/TimeSheets/p17>"
);
}) with objects {(
<TimeSheets: 0xc5557f0> (entity: TimeSheets; id: 0xc5537c0 <x-coredata://36042CA3-F392-46FB-AF23-F0C396CE0989/TimeSheets/p16> ; data: {
approvedBy = nil;
comments = nil;
dateApproved = nil;
dateEntered = "2013-09-11 17:05:11 +0000";
employee = "0xb4b8660 <x-coredata://36042CA3-F392-46FB-AF23-F0C396CE0989/Employees/p23>";
employeeID = 20;
enteredBy = 20;
hours = 205;
reportPeriod = nil;
reportPeriodID = 5;
task = "0xc561950 <x-coredata://36042CA3-F392-46FB-AF23-F0C396CE0989/Tasks/p9>";
taskID = 1915;
timeSheetDate = "2013-09-11 17:05:18 +0000";
timeSheetID = 2633;
timeStatus = nil;
timeStatusID = 1;
timeType = nil;
timeTypeID = 35;
}),
<TimeSheets: 0xc5559b0> (entity: TimeSheets; id: 0xc553810 <x-coredata://36042CA3-F392-46FB-AF23-F0C396CE0989/TimeSheets/p21> ; data: {
approvedBy = nil;
comments = Rarer;
dateApproved = nil;
dateEntered = "2013-09-17 22:05:11 +0000";
employee = "0xb4b8660 <x-coredata://36042CA3-F392-46FB-AF23-F0C396CE0989/Employees/p23>";
employeeID = 20;
enteredBy = 20;
hours = 0;
reportPeriod = nil;
reportPeriodID = 6;
task = "0xc561950 <x-coredata://36042CA3-F392-46FB-AF23-F0C396CE0989/Tasks/p9>";
taskID = 1915;
timeSheetDate = "2013-09-19 07:00:00 +0000";
timeSheetID = 3297;
timeStatus = nil;
timeStatusID = 1;
timeType = nil;
timeTypeID = 35;
}),
<TimeSheets: 0xc555950> (entity: TimeSheets; id: 0xc553800 <x-coredata://36042CA3-F392-46FB-AF23-F0C396CE0989/TimeSheets/p20> ; data: {
approvedBy = nil;
comments = Cbfb;
dateApproved = nil;
dateEntered = "2013-09-17 22:33:05 +0000";
employee = "0xb4b8660 <x-coredata://36042CA3-F392-46FB-AF23-F0C396CE0989/Employees/p23>";
employeeID = 20;
enteredBy = 20;
hours = 0;
reportPeriod = nil;
reportPeriodID = 6;
task = "0xc561950 <x-coredata://36042CA3-F392-46FB-AF23-F0C396CE0989/Tasks/p9>";
taskID = 1915;
timeSheetDate = "2013-09-16 07:00:00 +0000";
timeSheetID = 3298;
timeStatus = nil;
timeStatusID = 1;
timeType = nil;
timeTypeID = 35;
}),
<TimeSheets: 0xc5556c0> (entity: TimeSheets; id: 0xc553790 <x-coredata://36042CA3-F392-46FB-AF23-F0C396CE0989/TimeSheets/p13> ; data: {
approvedBy = nil;
comments = nil;
dateApproved = nil;
dateEntered = "2013-09-12 18:34:55 +0000";
employee = "0xb4b8660 <x-coredata://36042CA3-F392-46FB-AF23-F0C396CE0989/Employees/p23>";
employeeID = 20;
enteredBy = 20;
hours = 284;
reportPeriod = nil;
reportPeriodID = 5;
task = "0xc561950 <x-coredata://36042CA3-F392-46FB-AF23-F0C396CE0989/Tasks/p9>";
taskID = 1915;
timeSheetDate = "2013-09-12 18:21:59 +0000";
timeSheetID = 2827;
timeStatus = nil;
timeStatusID = 1;
timeType = nil;
timeTypeID = 35;
}),
<TimeSheets: 0xc555850> (entity: TimeSheets; id: 0xc5537d0 <x-coredata://36042CA3-F392-46FB-AF23-F0C396CE0989/TimeSheets/p17> ; data: {
approvedBy = nil;
comments = Asdad;
dateApproved = nil;
dateEntered = "2013-09-17 22:03:32 +0000";
employee = "0xb4b8660 <x-coredata://36042CA3-F392-46FB-AF23-F0C396CE0989/Employees/p23>";
employeeID = 20;
enteredBy = 20;
hours = 0;
reportPeriod = nil;
reportPeriodID = 6;
task = "0xc561950 <x-coredata://36042CA3-F392-46FB-AF23-F0C396CE0989/Tasks/p9>";
taskID = 1915;
timeSheetDate = "2013-09-15 07:00:00 +0000";
timeSheetID = 3296;
timeStatus = nil;
timeStatusID = 1;
timeType = nil;
timeTypeID = 35;
})
)}
)
Code For Double For Loop:
- (NSNumber *) getSumOfChargedHoursForAnArrayOfTasks: (NSArray *) tasksArray
{
NSArray *timeSheets = [tasksArray valueForKeyPath:#"timeSheets"];
NSNumber *chargedHours = [NSNumber numberWithInt:0];
for(int i = 0; i < [timeSheets count]; ++i)
{
NSArray *innerTimeSheet = [timeSheets objectAtIndex:i];
for(int j = 0; j < [innerTimeSheet count]; ++j)
{
NSNumber *innerNumber = [innerTimeSheet valueForKeyPath:#"#sum.hours"];
chargedHours = [NSNumber numberWithFloat:[chargedHours intValue] + [innerNumber intValue]];
}
}
return chargedHours;
}

Answer 1

If you are trying to sum the hours in all the time sheets in an array of tasks, then you should consider using valueForKeyPath: in the following way:
[tasks valueForKeyPath:#"#sum.timeSheets.#sum.hours"]
It appears that now, you are multiplying the sum of hours in the timeSheets for each task by the number of time sheets for each task.