How to store a Vec and its iterator in the same struct

Question

Given example codes as

#[derive(Default)]
pub struct Worker<'a>{
    v: Vec<i32>,
    m: HashMap<String, std::slice::Iter<'a, i32>>
}

impl<'a> Worker<'a> {
    pub fn new() -> Self {
        Worker::default()
    }

    pub fn seti(&mut self) {
        
    }

    pub fn setm(&'a mut self) {
        let v = self.v.iter();
        self.m.insert("sf".to_string(), v);
    }

    pub fn hello(&'a mut self) {
        self.setm();
        self.seti();
    }
}

where Worker.m is used to store iterators produced by Worker.v.

How to fix the broken codes above.

Desparate for help~