1.关于角度问题:
//图片旋转角度
//#define M_E 2.71828182845904523536028747135266250 /* e */
//#define M_LOG2E 1.44269504088896340735992468100189214 /* log2(e) */
//#define M_LOG10E 0.434294481903251827651128918916605082 /* log10(e) */
//#define M_LN2 0.693147180559945309417232121458176568 /* loge(2) */
//#define M_LN10 2.30258509299404568401799145468436421 /* loge(10) */
//#define M_PI 3.14159265358979323846264338327950288 /* pi */
//#define M_PI_2 1.57079632679489661923132169163975144 /* pi/2 */
//#define M_PI_4 0.785398163397448309615660845819875721 /* pi/4 */
//#define M_1_PI 0.318309886183790671537767526745028724 /* 1/pi */
//#define M_2_PI 0.636619772367581343075535053490057448 /* 2/pi */
//#define M_2_SQRTPI 1.12837916709551257389615890312154517 /* 2/sqrt(pi) */
//#define M_SQRT2 1.41421356237309504880168872420969808 /* sqrt(2) */
//#define M_SQRT1_2 0.707106781186547524400844362104849039 /* 1/sqrt(2) */
//图片旋转方式
// self.imgViewWheel.transform = CGAffineTransformMakeRotation(-M_PI_2);
// self.imgViewWheel.transform = CGAffineTransformMakeRotation(-M_PI);
// self.imgViewWheel.transform = CGAffineTransformMakeRotation(-M_1_PI);
// self.imgViewWheel.transform = CGAffineTransformMakeRotation(-M_2_PI);
// self.imgViewWheel.transform = CGAffineTransformMakeRotation(-M_2_SQRTPI);
// self.imgViewWheel.transform = CGAffineTransformMakeRotation(-M_SQRT2);
// self.imgViewWheel.transform = CGAffineTransformMakeRotation(-M_2_SQRTPI);
// self.imgViewWheel.transform = CGAffineTransformMakeRotation(-M_2_SQRTPI);
// self.imgViewWheel.transform = CGAffineTransformMakeRotation(-M_SQRT1_2);
2.关于旋转
//测试转动
//设置图片旋转速度(顺时针速度是M_PI_4 * 0.005)
// self.imgViewWheel.transform = CGAffineTransformRotate (self.imgViewWheel.transform, M_PI_4
// * 0.005);
//开始角度
// self.imgViewWheel.transform = CGAffineTransformMakeRotation (0);
//中间角度
// self.imgViewWheel.transform = CGAffineTransformMakeRotation (M_PI * 2 / 3);
//结束角度
// self.imgViewWheel.transform = CGAffineTransformMakeRotation (M_PI * 4 / 3);
3.关于线程和随机数
//每3秒执行一次线程
- (void)suijishu
{
NSLog (@"每3s将输出一个随机数");
// 在子线程中做事情
dispatch_async (dispatch_get_global_queue (0, 0), ^{
// 创建一个5s的定时器
NSTimer *timer = [NSTimer timerWithTimeInterval:3
target:self
selector:@selector (test)
userInfo:nil
repeats:YES];
// 需要将定时器添加到运行循环中
[[NSRunLoop currentRunLoop] addTimer:timer forMode:NSDefaultRunLoopMode];
// 在子线程中想要执行定时器,必须开启运行循环(这里就有一个死循环)
[[NSRunLoop currentRunLoop] run];
CFRunLoopRun ();
});
}
//生成一个随机数
- (void)test
{
//获取一个随机数范围在：[0,5）
float abcd = (arc4random () % 501);
self.num = M_PI * 4 * abcd / 1500;
NSLog (@"指针刻度:"
@"%.2f",
abcd / 100);
CFRunLoopStop (CFRunLoopGetCurrent ());
}
//让图片匀速旋转
//定义要旋转的View
{
UIView * pointView;
}
- (void)viewDidLoad
{
[self start];
}
//开始转动方法
- (void)start
{
CADisplayLink *link = [CADisplayLink displayLinkWithTarget:self selector:@selector (rotate)];
[link addToRunLoop:[NSRunLoop mainRunLoop] forMode:NSDefaultRunLoopMode];
}
//转动角度,速度控制
- (void)rotate
{
float num = M_PI * 4*30;
//设置图片旋转速度
pointView.transform = CGAffineTransformMakeRotation (num);
}