Make a choropleth map

AI-generated Key Takeaways

Choropleth maps display administrative areas colored based on data values, like population.
You can create choropleth maps using GMSFeatureLayer by associating areas with numeric ranges.
This example uses state population data to color states with varying hues based on population density.
Styling Places data might require using the Places SDK for iOS, although not always necessary.

A choropleth map is a type of thematic map in which administrative areas are colored or shaded according to a data value. You can use a GMSFeatureLayer to style a map based on data where each administrative area is associated with a range of numeric values.

A diagram showing a boundary choropleth
map

In this example, the data consists of an array of key-value pairs, matching the display name of each state with a numeric population value.

Swift

 //.. 
 let 
  
 featureLayer 
  
 = 
  
 mapView 
 . 
 featureLayer 
 ( 
 of 
 : 
  
 FeatureType 
 . 
 administrativeAreaLevel1 
 ) 
 let 
  
 populationOfStates 
  
 = 
  
 [ 
 "ChIJdf5LHzR_hogR6czIUzU0VV4" 
 : 
  
 5_039_877 
 , 
 "ChIJG8CuwJzfAFQRNduKqSde27w" 
 : 
  
 732673 
 , 
 "ChIJaxhMy-sIK4cRcc3Bf7EnOUI" 
 : 
  
 7_276_316 
 , 
 "ChIJYSc_dD-e0ocR0NLf_z5pBaQ" 
 : 
  
 3_025_891 
 , 
 "ChIJPV4oX_65j4ARVW8IJ6IJUYs" 
 : 
  
 39_237_836 
 , 
  
 // California 
 "ChIJt1YYm3QUQIcR_6eQSTGDVMc" 
 : 
  
 5_812_069 
 , 
 "ChIJpVER8hFT5okR5XBhBVttmq4" 
 : 
  
 3_605_597 
 , 
 "ChIJO9YMTXYFx4kReOgEjBItHZQ" 
 : 
  
 1_003_384 
 , 
 "ChIJvypWkWV2wYgR0E7HW9MTLvc" 
 : 
  
 21_781_128 
 , 
 "ChIJV4FfHcU28YgR5xBP7BC8hGY" 
 : 
  
 10_799_566 
 , 
 "ChIJBeB5Twbb_3sRKIbMdNKCd0s" 
 : 
  
 1_441_553 
 , 
 "ChIJ6Znkhaj_WFMRWIf3FQUwa9A" 
 : 
  
 1_900_923 
 , 
 "ChIJGSZubzgtC4gRVlkRZFCCFX8" 
 : 
  
 12_671_469 
 , 
 "ChIJHRv42bxQa4gRcuwyy84vEH4" 
 : 
  
 6_805_985 
 , 
 "ChIJGWD48W9e7ocR2VnHV0pj78Y" 
 : 
  
 3_193_079 
 , 
 "ChIJawF8cXEXo4cRXwk-S6m0wmg" 
 : 
  
 2_934_582 
 , 
 "ChIJyVMZi0xzQogR_N_MxU5vH3c" 
 : 
  
 4_509_394 
 , 
 "ChIJZYIRslSkIIYRA0flgTL3Vck" 
 : 
  
 4_624_047 
 , 
 "ChIJ1YpTHd4dsEwR0KggZ2_MedY" 
 : 
  
 1_372_247 
 , 
 "ChIJ35Dx6etNtokRsfZVdmU3r_I" 
 : 
  
 6_165_129 
 , 
 "ChIJ_b9z6W1l44kRHA2DVTbQxkU" 
 : 
  
 6_984_723 
 , 
 "ChIJEQTKxz2qTE0Rs8liellI3Zc" 
 : 
  
 10_050_811 
 , 
 "ChIJmwt4YJpbWE0RD6L-EJvJogI" 
 : 
  
 5_707_390 
 , 
 "ChIJGdRK5OQyKIYR2qbc6X8XDWI" 
 : 
  
 2_949_965 
 , 
 "ChIJfeMiSNXmwIcRcr1mBFnEW7U" 
 : 
  
 6_168_187 
 , 
 "ChIJ04p7LZwrQVMRGGwqz1jWcfU" 
 : 
  
 1_104_271 
 , 
 "ChIJ7fwMtciNk4cRxArzDwyQJ6E" 
 : 
  
 1_963_692 
 , 
 "ChIJcbTe-KEKmYARs5X8qooDR88" 
 : 
  
 3_143_991 
 , 
 "ChIJ66bAnUtEs0wR64CmJa8CyNc" 
 : 
  
 1_388_992 
 , 
 "ChIJn0AAnpX7wIkRjW0_-Ad70iw" 
 : 
  
 9_267_130 
 , 
 "ChIJqVKY50NQGIcRup41Yxpuv0Y" 
 : 
  
 2_115_877 
 , 
 "ChIJqaUj8fBLzEwRZ5UY3sHGz90" 
 : 
  
 19_835_913 
 , 
 "ChIJgRo4_MQfVIgRGa4i6fUwP60" 
 : 
  
 10_551_162 
 , 
 "ChIJY-nYVxKD11IRyc9egzmahA0" 
 : 
  
 774948 
 , 
 "ChIJwY5NtXrpNogRFtmfnDlkzeU" 
 : 
  
 11_780_017 
 , 
 "ChIJnU-ssRE5rIcRSOoKQDPPHF0" 
 : 
  
 3_986_639 
 , 
 "ChIJVWqfm3xuk1QRdrgLettlTH0" 
 : 
  
 4_246_155 
 , 
 "ChIJieUyHiaALYgRPbQiUEchRsI" 
 : 
  
 12_964_056 
 , 
 "ChIJD9cOYhQ15IkR5wbB57wYTh4" 
 : 
  
 1_095_610 
 , 
 "ChIJ49ExeWml-IgRnhcF9TKh_7k" 
 : 
  
 5_190_705 
 , 
 "ChIJpTjphS1DfYcRt6SGMSnW8Ac" 
 : 
  
 895376 
 , 
 "ChIJA8-XniNLYYgRVpGBpcEgPgM" 
 : 
  
 6_975_218 
 , 
 "ChIJSTKCCzZwQIYRPN4IGI8c6xY" 
 : 
  
 29_527_941 
 , 
 "ChIJzfkTj8drTIcRP0bXbKVK370" 
 : 
  
 3_337_975 
 , 
 "ChIJ_87aSGzctEwRtGtUNnSJTSY" 
 : 
  
 645570 
 , 
 "ChIJzbK8vXDWTIgRlaZGt0lBTsA" 
 : 
  
 8_642_274 
 , 
 "ChIJ-bDD5__lhVQRuvNfbGh4QpQ" 
 : 
  
 7_738_692 
 , 
 "ChIJRQnL1KVUSogRQzrN3mjHALs" 
 : 
  
 1_782_959 
 , 
 "ChIJr-OEkw_0qFIR1kmG-LjV1fI" 
 : 
  
 5_895_908 
 , 
 "ChIJaS7hSDTiXocRLzh90nkisCY" 
 : 
  
 578803 
 , 
  
 // Wyoming 
 ] 
 featureLayer 
 . 
 style 
  
 = 
  
 { 
  
 feature 
  
 in 
  
 FeatureStyle 
 ( 
  
 fill 
 : 
  
 populationOfStates 
 [ 
 feature 
 . 
 placeID 
 ]. 
 map 
  
 { 
  
 UIColor 
 ( 
  
 hue 
 : 
  
 log 
 ( 
 CGFloat 
 ( 
 $0 
 ) 
  
 / 
  
 5e5 
 ) 
  
 / 
  
 7.5 
 , 
  
 saturation 
 : 
  
 1 
 , 
  
 brightness 
 : 
  
 0.75 
 , 
  
 alpha 
 : 
  
 0.5 
 ) 
  
 } 
  
 ?? 
  
 nil 
 , 
  
 stroke 
 : 
  
 nil 
 , 
  
 strokeWidth 
 : 
  
 0 
  
 ) 
 } 
 self 
 . 
 view 
  
 = 
  
 mapView

Objective-C

 //.. 
 GMSFeatureLayer<GMSPlaceFeature 
 *> 
* featureLayer 
  
 = 
  
 [ 
 mapView 
  
 featureLayerOfFeatureType 
 : 
 GMSFeatureTypeAdministrativeAreaLevel1 
 ]; 
 NSDictionary<NSString 
  
* , 
  
 NSNumber 
 *> 
 * 
 populationOfStates 
  
 = 
  
 @{ 
  
 @"ChIJdf5LHzR_hogR6czIUzU0VV4" 
  
 : 
  
 @( 
 5039877 
 ) 
 , 
  
 @"ChIJG8CuwJzfAFQRNduKqSde27w" 
  
 : 
  
 @( 
 732673 
 ) 
 , 
  
 @"ChIJaxhMy-sIK4cRcc3Bf7EnOUI" 
  
 : 
  
 @( 
 7276316 
 ) 
 , 
  
 @"ChIJYSc_dD-e0ocR0NLf_z5pBaQ" 
  
 : 
  
 @( 
 3025891 
 ) 
 , 
  
 @"ChIJPV4oX_65j4ARVW8IJ6IJUYs" 
  
 : 
  
 @( 
 39237836 
 ) 
 , 
  
 // California 
  
 @"ChIJt1YYm3QUQIcR_6eQSTGDVMc" 
  
 : 
  
 @( 
 5812069 
 ) 
 , 
  
 @"ChIJpVER8hFT5okR5XBhBVttmq4" 
  
 : 
  
 @( 
 3605597 
 ) 
 , 
  
 @"ChIJO9YMTXYFx4kReOgEjBItHZQ" 
  
 : 
  
 @( 
 1003384 
 ) 
 , 
  
 @"ChIJvypWkWV2wYgR0E7HW9MTLvc" 
  
 : 
  
 @( 
 21781128 
 ) 
 , 
  
 @"ChIJV4FfHcU28YgR5xBP7BC8hGY" 
  
 : 
  
 @( 
 10799566 
 ) 
 , 
  
 @"ChIJBeB5Twbb_3sRKIbMdNKCd0s" 
  
 : 
  
 @( 
 1441553 
 ) 
 , 
  
 @"ChIJ6Znkhaj_WFMRWIf3FQUwa9A" 
  
 : 
  
 @( 
 1900923 
 ) 
 , 
  
 @"ChIJGSZubzgtC4gRVlkRZFCCFX8" 
  
 : 
  
 @( 
 12671469 
 ) 
 , 
  
 @"ChIJHRv42bxQa4gRcuwyy84vEH4" 
  
 : 
  
 @( 
 6805985 
 ) 
 , 
  
 @"ChIJGWD48W9e7ocR2VnHV0pj78Y" 
  
 : 
  
 @( 
 3193079 
 ) 
 , 
  
 @"ChIJawF8cXEXo4cRXwk-S6m0wmg" 
  
 : 
  
 @( 
 2934582 
 ) 
 , 
  
 @"ChIJyVMZi0xzQogR_N_MxU5vH3c" 
  
 : 
  
 @( 
 4509394 
 ) 
 , 
  
 @"ChIJZYIRslSkIIYRA0flgTL3Vck" 
  
 : 
  
 @( 
 4624047 
 ) 
 , 
  
 @"ChIJ1YpTHd4dsEwR0KggZ2_MedY" 
  
 : 
  
 @( 
 1372247 
 ) 
 , 
  
 @"ChIJ35Dx6etNtokRsfZVdmU3r_I" 
  
 : 
  
 @( 
 6165129 
 ) 
 , 
  
 @"ChIJ_b9z6W1l44kRHA2DVTbQxkU" 
  
 : 
  
 @( 
 6984723 
 ) 
 , 
  
 @"ChIJEQTKxz2qTE0Rs8liellI3Zc" 
  
 : 
  
 @( 
 10050811 
 ) 
 , 
  
 @"ChIJmwt4YJpbWE0RD6L-EJvJogI" 
  
 : 
  
 @( 
 5707390 
 ) 
 , 
  
 @"ChIJGdRK5OQyKIYR2qbc6X8XDWI" 
  
 : 
  
 @( 
 2949965 
 ) 
 , 
  
 @"ChIJfeMiSNXmwIcRcr1mBFnEW7U" 
  
 : 
  
 @( 
 6168187 
 ) 
 , 
  
 @"ChIJ04p7LZwrQVMRGGwqz1jWcfU" 
  
 : 
  
 @( 
 1104271 
 ) 
 , 
  
 @"ChIJ7fwMtciNk4cRxArzDwyQJ6E" 
  
 : 
  
 @( 
 1963692 
 ) 
 , 
  
 @"ChIJcbTe-KEKmYARs5X8qooDR88" 
  
 : 
  
 @( 
 3143991 
 ) 
 , 
  
 @"ChIJ66bAnUtEs0wR64CmJa8CyNc" 
  
 : 
  
 @( 
 1388992 
 ) 
 , 
  
 @"ChIJn0AAnpX7wIkRjW0_-Ad70iw" 
  
 : 
  
 @( 
 9267130 
 ) 
 , 
  
 @"ChIJqVKY50NQGIcRup41Yxpuv0Y" 
  
 : 
  
 @( 
 2115877 
 ) 
 , 
  
 @"ChIJqaUj8fBLzEwRZ5UY3sHGz90" 
  
 : 
  
 @( 
 19835913 
 ) 
 , 
  
 @"ChIJgRo4_MQfVIgRGa4i6fUwP60" 
  
 : 
  
 @( 
 10551162 
 ) 
 , 
  
 @"ChIJY-nYVxKD11IRyc9egzmahA0" 
  
 : 
  
 @( 
 774948 
 ) 
 , 
  
 @"ChIJwY5NtXrpNogRFtmfnDlkzeU" 
  
 : 
  
 @( 
 11780017 
 ) 
 , 
  
 @"ChIJnU-ssRE5rIcRSOoKQDPPHF0" 
  
 : 
  
 @( 
 3986639 
 ) 
 , 
  
 @"ChIJVWqfm3xuk1QRdrgLettlTH0" 
  
 : 
  
 @( 
 4246155 
 ) 
 , 
  
 @"ChIJieUyHiaALYgRPbQiUEchRsI" 
  
 : 
  
 @( 
 12964056 
 ) 
 , 
  
 @"ChIJD9cOYhQ15IkR5wbB57wYTh4" 
  
 : 
  
 @( 
 1095610 
 ) 
 , 
  
 @"ChIJ49ExeWml-IgRnhcF9TKh_7k" 
  
 : 
  
 @( 
 5190705 
 ) 
 , 
  
 @"ChIJpTjphS1DfYcRt6SGMSnW8Ac" 
  
 : 
  
 @( 
 895376 
 ) 
 , 
  
 @"ChIJA8-XniNLYYgRVpGBpcEgPgM" 
  
 : 
  
 @( 
 6975218 
 ) 
 , 
  
 @"ChIJSTKCCzZwQIYRPN4IGI8c6xY" 
  
 : 
  
 @( 
 29527941 
 ) 
 , 
  
 @"ChIJzfkTj8drTIcRP0bXbKVK370" 
  
 : 
  
 @( 
 3337975 
 ) 
 , 
  
 @"ChIJ_87aSGzctEwRtGtUNnSJTSY" 
  
 : 
  
 @( 
 645570 
 ) 
 , 
  
 @"ChIJzbK8vXDWTIgRlaZGt0lBTsA" 
  
 : 
  
 @( 
 8642274 
 ) 
 , 
  
 @"ChIJ-bDD5__lhVQRuvNfbGh4QpQ" 
  
 : 
  
 @( 
 7738692 
 ) 
 , 
  
 @"ChIJRQnL1KVUSogRQzrN3mjHALs" 
  
 : 
  
 @( 
 1782959 
 ) 
 , 
  
 @"ChIJr-OEkw_0qFIR1kmG-LjV1fI" 
  
 : 
  
 @( 
 5895908 
 ) 
 , 
  
 @"ChIJaS7hSDTiXocRLzh90nkisCY" 
  
 : 
  
 @( 
 578803 
 ) 
 , 
  
 // Wyoming 
 } 
 ; 
 featureLayer 
 . 
 style 
  
 = 
  
 ^ 
 ( 
 GMSPlaceFeature 
  
 * 
 feature 
 ) 
  
 { 
  
 NSNumber 
  
 * 
 population 
  
 = 
  
 populationOfStates 
 [ 
 feature 
 . 
 placeID 
 ]; 
  
 UIColor 
  
 * 
 fillColor 
  
 = 
  
 population 
  
 ? 
  
 [ 
 UIColor 
  
 colorWithHue 
 : 
 ( 
 log 
 ( 
 population 
 . 
 doubleValue 
  
 / 
  
 5e5 
 ) 
  
 / 
  
 7.5 
 ) 
  
 saturation 
 : 
 1 
  
 brightness 
 : 
 0.5 
  
 alpha 
 : 
 0.5 
 ] 
  
 : 
  
 nil 
 ; 
  
 return 
  
 [ 
 GMSFeatureStyle 
  
 styleWithFillColor 
 : 
 fillColor 
  
 strokeColor 
 : 
 nil 
  
 strokeWidth 
 : 
 0.0 
 ]; 
 }; 
 self 
 . 
 view 
  
 = 
  
 mapView 
 ;

Make a choropleth map Stay organized with collections Save and categorize content based on your preferences.

AI-generated Key Takeaways

Swift

Objective-C

Make a choropleth map