executing shell command with | (pipe) using NSTask

I'm trying to execute this comamnd ps -ef | grep test using NSTask but I can't get the | grep test to be included in the NSTask:

This is what I'm using currently to get the output of ps -ef into a string then I need to somehow get the pid of the process test

NSTask *task;
task = [[NSTask alloc] init];
[task setLaunchPath: @"/bin/ps"];

NSArray *arguments;
arguments = [NSArray arrayWithObjects: @"-ef", nil];
[task setArguments: arguments];    
NSPipe *pipe;
pipe = [NSPipe pipe];
[task setStandardOutput: pipe];

NSFileHandle *file;
file = [pipe fileHandleForReading];

[task launch];

NSData *data;
data = [file readDataToEndOfFile];

NSString *string;
string = [[NSString alloc] initWithData: data
                               encoding: NSUTF8StringEncoding];
NSLog (@"got\n%@", string);