iphone开发之设备方向和角度计算

没什么好说的代码如下

头文件////////////

/*
Erica Sadun, http://ericasadun.com
iPhone Developer's Cookbook, 3.0 Edition
BSD License, Use at your own risk
*/

#import <UIKit/UIKit.h>


@interface UIDevice (Orientation) <UIAccelerometerDelegate>
- (BOOL) isLandscape;
- (BOOL) isPortrait;
- (NSString *) orientationString;
- (float) orientationAngleRelativeToOrientation:(UIDeviceOrientation) someOrientation;
@property (nonatomic, readonly) BOOL isLandscape;
@property (nonatomic, readonly) BOOL isPortrait;
@property (nonatomic, readonly) NSString *orientationString;
@property (nonatomic, readonly) float orientationAngle;
@end

实现文件///////////

/*
Erica Sadun, http://ericasadun.com
iPhone Developer's Cookbook, 3.0 Edition
BSD License, Use at your own risk
*/

// Thanks jweinberg, Emanuele Vulcano, rincewind42, Jonah Williams

#import "UIDevice-Orientation.h"

@implementation UIDevice (Orientation)

float device_angle;
CFRunLoopRef currentLoop;

- (void)accelerometer:(UIAccelerometer *)accelerometer didAccelerate:(UIAcceleration *)acceleration
{
float xx = [acceleration x];
float yy = -[acceleration y];
device_angle = M_PI / 2.0f - atan2(yy, xx);

CFRunLoopStop(currentLoop);
}

- (float) orientationAngle
{
#if TARGET_IPHONE_SIMULATOR
// NSLog( @"Running in the simulator!" );
switch (self.orientation)
{
case UIDeviceOrientationPortrait:
return 0.0f;
case UIDeviceOrientationPortraitUpsideDown:
return M_PI;
case UIDeviceOrientationLandscapeLeft:
return -(M_PI/2.0f);
case UIDeviceOrientationLandscapeRight:
return (M_PI/2.0f);
default:
return 0.0f;
}
#else
id accelerometer_delegate = [UIAccelerometer sharedAccelerometer].delegate;
[UIAccelerometer sharedAccelerometer].delegate = self;

// Wait for a reading
currentLoop = CFRunLoopGetCurrent();
CFRunLoopRun();
[UIAccelerometer sharedAccelerometer].delegate = accelerometer_delegate;

return device_angle;
#endif
}

// Thanks Jonah Williams
- (float) orientationAngleRelativeToOrientation:(UIDeviceOrientation) someOrientation
{
float dOrientation = 0.0f;
switch (someOrientation)
{
case UIDeviceOrientationPortraitUpsideDown: {dOrientation = M_PI; break;}
case UIDeviceOrientationLandscapeLeft: {dOrientation = -(M_PI/2.0f); break;}
case UIDeviceOrientationLandscapeRight: {dOrientation = (M_PI/2.0f); break;}
default: break;
}

float adjustedAngle = fmod(self.orientationAngle - dOrientation, 2.0f * M_PI);
if (adjustedAngle > (M_PI + 0.01f)) adjustedAngle = (adjustedAngle - 2.0f * M_PI);
return adjustedAngle;
}

- (BOOL) isLandscape
{
return UIDeviceOrientationIsLandscape(self.orientation);
}

- (BOOL) isPortrait
{
return UIDeviceOrientationIsPortrait(self.orientation);
}

- (NSString *) orientationString
{
switch ([[UIDevice currentDevice] orientation])
{
case UIDeviceOrientationUnknown: return @"Unknown";
case UIDeviceOrientationPortrait: return @"Portrait";
case UIDeviceOrientationPortraitUpsideDown: return @"Portrait Upside Down";
case UIDeviceOrientationLandscapeLeft: return @"Landscape Left";
case UIDeviceOrientationLandscapeRight: return @"Landscape Right";
case UIDeviceOrientationFaceUp: return @"Face Up";
case UIDeviceOrientationFaceDown: return @"Face Down";
default: break;
}
return nil;
}
@end