how to use a Class Breaks Renderer in the ESRI ArcGIS iPhone API to display cities of varying population with different

Code Listings

ClassBreaksViewController.h

01	#import <UIKit/UIKit.h>

02	#import "AGSiPhone.h"

03

04	#define kTiledMapServiceURL @"http://server.arcgisonline.com/ArcGIS/rest/services/ESRI_Imagery_World_2D/MapServer"

05	#define kDynamicMapServiceURL @"http://sampleserver1.arcgisonline.com/ArcGIS/rest/services/Specialty/ESRI_StatesCitiesRivers_USA/MapServer/0"

06

07	@interface ClassBreaksViewController : UIViewController<AGSMapViewDelegate, AGSQueryTaskDelegate> {

08	AGSMapView *mapView;

09	AGSGraphicsLayer *cityGraphicsLayer;

10	AGSQueryTask *cityQueryTask;

11

12

}

13

14	@property (nonatomic, retain) IBOutlet AGSMapView *mapView;

15	@property (nonatomic, retain) AGSGraphicsLayer *cityGraphicsLayer;

16	@property (nonatomic, retain) AGSQueryTask *cityQueryTask;

17

18

@end

ClassBreaksViewController.m

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001	#import "ClassBreaksViewController.h"

002

003	@implementation ClassBreaksViewController

004

005	@synthesize mapView;

006	@synthesize cityGraphicsLayer;

007	@synthesize cityQueryTask;

008

009	// Implement viewDidLoad to do additional setup after loading the view, typically from a nib.

010	- (void)viewDidLoad {

011	[super viewDidLoad];

012

013	// Set map view delegate

014	self.mapView.mapViewDelegate = self;

015

016	// Create tile base map layer

017	AGSTiledMapServiceLayer *tiledLayer = [[AGSTiledMapServiceLayer alloc] initWithURL:[NSURL URLWithString:kTiledMapServiceURL]];

018	[self.mapView addMapLayer:tiledLayer withName:@"BaseLayer"];

019	[tiledLayer release];

020

021	// Create grpahics layer

022	self.cityGraphicsLayer = [AGSGraphicsLayer graphicsLayer];

023

024	// Create symbols for the three class breaks

025	AGSSimpleMarkerSymbol *lowSymbol = [AGSSimpleMarkerSymbol simpleMarkerSymbol];

026	lowSymbol.color = [UIColor colorWithRed:151.0/255.0 green:216.0/255.0 blue:255.0/255.0 alpha:0.8];

027	lowSymbol.outline.width = 0;

028	lowSymbol.size = 15;

029

030	AGSSimpleMarkerSymbol *mediumSymbol = [AGSSimpleMarkerSymbol simpleMarkerSymbol];

031	mediumSymbol.color = [UIColor colorWithRed:255.0/255.0 green:165.0/255.0 blue:83.0/255.0 alpha:0.8];

032	mediumSymbol.outline.width = 0;

033	mediumSymbol.size = 20;

034

035	AGSSimpleMarkerSymbol *highSymbol = [AGSSimpleMarkerSymbol simpleMarkerSymbol];

036	highSymbol.color = [UIColor colorWithRed:222.0/255.0 green:0.0 blue:0.0 alpha:0.8];

037	highSymbol.outline.width = 0;

038	highSymbol.size = 25;

039

040	// Create a class breaks renderer with a default simple marker symbol and an attribute field

041	AGSClassBreaksRenderer *cityRenderer = [AGSClassBreaksRenderer

042	classBreaksRendererWithDefaultSymbol:lowSymbol

043	forAttributeField:@"POP1990"];

044

045	// Create three AGSClassBreak objects, one each for low, medium and high populations

046	AGSClassBreak* lowClassBreak = [AGSClassBreak

047	classBreakInfoWithSymbol:lowSymbol forMinValue:DBL_MIN

048	maxValue:50000.0];

049

050	AGSClassBreak* mediumClassBreak = [AGSClassBreak

051	classBreakInfoWithSymbol:mediumSymbol forMinValue:50000.0

052	maxValue:250000];

053

054	AGSClassBreak* highClassBreak = [AGSClassBreak

055	classBreakInfoWithSymbol:highSymbol forMinValue:250000.0

056	maxValue:DBL_MAX];

057

058	// Create an NSMutableArray, fill it with the class break objects,

059	// and set it to the renderer’s classBreaks property

060	cityRenderer.classBreaks = [NSMutableArray arrayWithObjects:

061	lowClassBreak, mediumClassBreak, highClassBreak, nil];

062

063	// Add the renderer to the graphics layer

064	self.cityGraphicsLayer.renderer = cityRenderer;

065

066	// Add the graphics layer to the map view

067	[self.mapView addMapLayer:self.cityGraphicsLayer withName:@"CityGraphicsLayer"];

068

}

069

070	// Override to allow orientations other than the default portrait orientation.

071	- (BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)interfaceOrientation {

072	// Return YES for supported orientations

073	return YES;

074

}

075

076	- (void)didReceiveMemoryWarning {

077	// Releases the view if it doesn't have a superview.

078	[super didReceiveMemoryWarning];

079

080	// Release any cached data, images, etc that aren't in use.

081

}

082

083	- (void)viewDidUnload {

084	// Release any retained subviews of the main view.

085	// e.g. self.myOutlet = nil;

086	self.cityGraphicsLayer = nil;

087	self.mapView = nil;

088	[super viewDidUnload];

089

}

090

091	- (void)dealloc {

092	[cityGraphicsLayer release];

093	[mapView release];

094	[super dealloc];

095

}

096

097	#pragma mark AGSMapViewDelegate

098

099	// Called when the map view is loaded (after the view is loaded)

100	- (void)mapViewDidLoad:(AGSMapView *)mapView {

101

102	// Set up query task for cities and perform query returning all attributes

103	self.cityQueryTask = [AGSQueryTask queryTaskWithURL:[NSURL URLWithString:kDynamicMapServiceURL]];

104	self.cityQueryTask.delegate = self;

105

106	AGSQuery *cityQuery = [AGSQuery query];

107	cityQuery.where = @"STATE_NAME = 'California'";

108	cityQuery.outFields = [NSArray arrayWithObject:@"*"];

109

110	[self.cityQueryTask executeWithQuery:cityQuery];

111

112	// Create extent to be used as default

113	AGSEnvelope *envelope = [AGSEnvelope envelopeWithXmin:-118.6

114

ymin:33.6

115	xmax:-118.1

116

ymax:34.2

117	spatialReference:self.mapView.spatialReference];

118

119	// Call method to set extent, pass in envelope

120	[self.mapView performSelector:@selector(zoomToEnvelope:animated:)

121	withObject:envelope

122	afterDelay:0.5];

123

}

124

125	#pragma mark AGSQueryTaskDelegate

126

127	// When query is executed ....

128	- (void)queryTask:(AGSQueryTask *)queryTask didExecuteWithFeatureSetResult:(AGSFeatureSet *)featureSet {

129	// Iterate the returned features (graphics) and add them to the graphics layer

130	for (AGSGraphic *graphic in featureSet.features) {

131	[self.cityGraphicsLayer addGraphic:graphic];

132

}

133	[self.cityGraphicsLayer dataChanged];

134

135	// Clean up query task memory

136	self.cityQueryTask = nil;

137

}

138

139	// If there's an error with the query task give info to user

140	- (void)queryTask:(AGSQueryTask *)queryTask didFailWithError:(NSError *)error {

141	// Clean up query task memory

142	self.cityQueryTask = nil;

143

144	// Display error message

145	UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"Error"

146	message:[error localizedDescription]

147	delegate:nil

148	cancelButtonTitle:@"OK"

149	otherButtonTitles:nil];

150	[alert show];

151	[alert release];

152

}

153

154

@end