makeicon | Generates mobile app icons in all resolutions for both iOS | Mobile Application library

library(shiny)
library(shinyWidgets)
library(leaflet)
library(leaflegend)
library(dplyr)
library(sp)
library(raster)
library(rgdal)
library(rgeos)
points <- c("A", "A", "B", "B")
lat <- c(9,10,11,10)
lon <- c(11,10,2,12)
type <- c(alpha= "alpha",beta = "beta",theta = "theta",gamma = "gamma")

df <- data.frame(points,lat,lon,type)

coordinates(df)<-~lat+lon
proj4string(df) <- CRS("+proj=longlat +datum=WGS84 +no_defs")

ui <- bootstrapPage(
    tags$style(type = "text/css", "html, body {width:100%;height:100%}"),
    leafletOutput("map1", width = "100%", height = "100%"),
    absolutePanel(left = 10, bottom = 10, draggable = TRUE, 
                  selectInput(inputId = "input_letter", label = "Select Letter",
                              choices = c("A","B")),
                  selectInput(inputId = "input_gr_letter", label = "Select Gr Letter",
                              choices = c("alpha","beta","theta","gamma"),
                              multiple = TRUE)
    ))  

# List of Icons
listofIcons <- iconList(
    alpha = makeIcon(iconUrl = "https://img.icons8.com/emoji/48/000000/yellow-circle-emoji.png", iconWidth = 10, iconHeight = 10),
    beta = makeIcon(iconUrl = "https://img.icons8.com/emoji/48/000000/orange-circle-emoji.png", iconWidth = 10, iconHeight = 10),
    theta = makeIcon(iconUrl = "https://img.icons8.com/emoji/48/000000/purple-circle-emoji.png", iconWidth = 10, iconHeight = 10),
    gamma = makeIcon(iconUrl = "https://img.icons8.com/emoji/48/000000/red-circle-emoji.png", iconWidth = 10, iconHeight = 10)
)


server <- function(input, output, session) {
    
    # Create the map
    output$map1 <- renderLeaflet({
        leaflet(
            option = leafletOptions(attributionControl=FALSE)) %>%
            addTiles() 
    })
    
    data_point <- reactive({
        df[df@data$points == input$input_letter & df@data$type %in% input$input_gr_letter,]
    })
    
    
    # Reactive Map ---------------------------------
    imgs <- c(alpha = "https://img.icons8.com/emoji/48/000000/yellow-circle-emoji.png",
              beta =  "https://img.icons8.com/emoji/48/000000/orange-circle-emoji.png",
              theta = "https://img.icons8.com/emoji/48/000000/purple-circle-emoji.png",
              gamma = "https://img.icons8.com/emoji/48/000000/red-circle-emoji.png")
    observeEvent(list(input$input_letter, input$input_gr_letter), {
        if(is.null(input$input_gr_letter)) return(leafletProxy("map1") %>% removeControl("legend"))
        leafletProxy("map1") %>%
            addMarkers(data = data_point(),
                       icon = ~listofIcons[type]) %>%
            removeControl("legend") %>% 
            addLegendImage(images = imgs[input$input_gr_letter],
                           labels = type[input$input_gr_letter], layerId = "legend")
    }, ignoreInit = T)
}

shinyApp(ui, server)