Learning iOS Programming, 3rd Edition

Chapter 9. Using Sensors

Mobile phones aren’t just for making phone calls anymore. The iPhone, like a lot of high-end smartphones these days, comes with a number of sensors: camera, accelerometer, GPS module, and digital compass. We’re entering a period of change: more and more users expect these sensors to be integrated into the “application experience.” If your application can make use of them, it probably should.

Hardware Support

Unique among modern mobile platforms, Apple has gone to great lengths to ensure that your code will run on all of the current iOS-based devices. Yet despite this, there is still some variation in hardware between the various models (see Table 9-1).

Table 9-1. Hardware support in various iPhone, iPod touch, and iPad models

Hardware features	iPhone				iPod touch					iPad		iPad 2		New iPad		iPad Mini
	3G	3GS	4 and 4S	5	1st gen	2nd gen	3rd gen	4th gen	5th gen	WiFi	3G	WiFi	3G	WiFi	3G	WiFi	3G
Cellular	✓	✓	✓	✓	✗	✗	✗	✗	✗	✗	✓	✓	✓	✓	✓	✓	✓
WiFi	✓	✓	✓	✓	✓	✓	✓	✓	✓	✓	✓	✓	✓	✓	✓	✓	✓
Bluetooth	✓	✓	✓	✓	✗	✓	✓	✓	✓	✓	✓	✓	✓	✓	✓	✓	✓
Speaker	✓	✓	✓	✓	✗	✓	✓	✓	✓	✓	✓	✓	✓	✓	✓	✓	✓
Audio In	✓	✓	✓	✓	✗	✓	✓	✓	✓	✓	✓	✓	✓	✓	✓	✓	✓
Accelerometer	✓	✓	✓	✓	✓	✓	✓	✓	✓	✓	✓	✓	✓	✓	✓	✓	✓
Magnetometer	✗	✓	✓	✓	✗	✗	✗	✗	✗	✓	✓	✓	✓	✓	✓	✓	✓
Gyroscope	✗	✗	✓	✓	✗	✗	✗	✓	✓	✗	✗	✓	✓	✓	✓	✓	✓
GPS	✓	✓	✓	✓	✗	✗	✗	✗	✗	✗	✓	✗	✓	✗	✓	✗	✓
Proximity Sensor