变换CALayer锚点实现模拟时钟的动画

变换CALayer锚点实现模拟时钟的动画

变换锚点得需要一点理论知识,看下图就能明白:).

https://developer.apple.com/library/ios/documentation/Cocoa/Conceptual/CoreAnimation_guide/CoreAnimationBasics/CoreAnimationBasics.html#//apple_ref/doc/uid/TP40004514-CH2-SW15

开始实现模拟时钟效果:

//
//  RootViewController.m
//
//  Copyright (c) 2014年 Y.X. All rights reserved.
//

#import "RootViewController.h"
#import "YXGCD.h"

@interface RootViewController ()

@property (nonatomic, strong) GCDTimer *timer;

@end

// 将角度转换为弧度
#define DEGREES__TO__RADIANS(d)  ((d) * M_PI / 180.f)

@implementation RootViewController

- (void)viewDidLoad
{
    [super viewDidLoad];

    // 显示参考用的view
    UIView *showView = [[UIView alloc] initWithFrame:CGRectMake(, , , )];
    showView.layer.borderWidth = .f;
    showView.layer.cornerRadius = .f;
    showView.layer.borderColor = [UIColor redColor].CGColor;
    showView.center = self.view.center;
    [self.view addSubview:showView];

    // 新建layer
    CALayer *layer = [CALayer layer];
    layer.backgroundColor = [UIColor blackColor].CGColor;

    // 重置锚点
    layer.anchorPoint = CGPointMake(.f, .f);

    // 设置layer的frame值(在showView正中间摆放)
    layer.frame = CGRectMake(showView.middleX, showView.middleY, , );

    // 添加进showView中
    [showView.layer addSublayer:layer];

    // 定时器
    _timer = [[GCDTimer alloc] initInQueue:[GCDQueue mainQueue]];
    [_timer event:^{
        static int i = ;

        // 每秒增加的角度
        layer.transform = \
            CATransform3DMakeRotation(DEGREES__TO__RADIANS((/.f) * i++), 0.0, 0.0, 1.0);
    } timeInterval:NSEC_PER_SEC];
    [_timer start];
}

@end

重要的代码:

以下是最终效果:

完整代码:

//
//  RootViewController.m
//
//  Copyright (c) 2014年 Y.X. All rights reserved.
//

#import "RootViewController.h"
#import "YXGCD.h"

static NSDateFormatter* _DMLogDateFormatter = nil;

@interface RootViewController ()

@property (nonatomic, strong) GCDTimer *timer;
@property (nonatomic, strong) UILabel  *timeLabel;

@end

// 将角度转换为弧度
#define DEGREES__TO__RADIANS(d)  ((d) * M_PI / 180.f)

@implementation RootViewController

- (void)viewDidLoad
{
    [super viewDidLoad];
    self.view.backgroundColor = [UIColor blackColor];

    // 日期格式
    _DMLogDateFormatter = [[NSDateFormatter alloc] init];
    [_DMLogDateFormatter setLocale:[[NSLocale alloc] initWithLocaleIdentifier:@"en_US_POSIX"]];
    [_DMLogDateFormatter setDateFormat:@"HH:mm:ss"];

    // 显示label
    _timeLabel = [[UILabel alloc] initWithFrame:CGRectMake(, , , )];
    _timeLabel.textAlignment = NSTextAlignmentCenter;
    _timeLabel.font = [UIFont fontWithName:@"HelveticaNeue-Thin" size:.f];
    _timeLabel.textColor = [UIColor cyanColor];
    _timeLabel.center = self.view.center;
    _timeLabel.y += ;
    [self.view addSubview:_timeLabel];

    // 显示参考用的view
    UIView *showView = [[UIView alloc] initWithFrame:CGRectMake(, , , )];
    showView.layer.borderWidth = .f;
    showView.layer.cornerRadius = .f;
    showView.layer.borderColor = [UIColor redColor].CGColor;
    showView.center = self.view.center;
    [self.view addSubview:showView];

    // 新建秒钟Layer
    // ----------------------------------------------------- //
    CALayer *secondLayer = [CALayer layer];
    secondLayer.backgroundColor = [UIColor whiteColor].CGColor;

    // 重置锚点
    secondLayer.anchorPoint = CGPointMake(.f, .f);

    // 设置layer的frame值(在showView正中间摆放)
    secondLayer.frame = CGRectMake(showView.middleX, showView.middleY, , );

    // 添加进showView中
    [showView.layer addSublayer:secondLayer];

    // 新建分钟Layer
    // ----------------------------------------------------- //
    CALayer *minuteLayer = [CALayer layer];
    minuteLayer.backgroundColor = [UIColor greenColor].CGColor;

    // 重置锚点
    minuteLayer.anchorPoint = CGPointMake(.f, .f);

    // 设置layer的frame值(在showView正中间摆放)
    minuteLayer.frame = CGRectMake(showView.middleX, showView.middleY, , );

    // 添加进showView中
    [showView.layer addSublayer:minuteLayer];

    // 新建时钟Layer
    // ----------------------------------------------------- //
    CALayer *hourLayer = [CALayer layer];
    hourLayer.backgroundColor = [UIColor blueColor].CGColor;

    // 重置锚点
    hourLayer.anchorPoint = CGPointMake(.f, .f);

    // 设置layer的frame值(在showView正中间摆放)
    hourLayer.frame = CGRectMake(showView.middleX, showView.middleY, , );

    // 添加进showView中
    [showView.layer addSublayer:hourLayer];

    // 定时器
    _timer = [[GCDTimer alloc] initInQueue:[GCDQueue mainQueue]];
    [_timer event:^{

        NSString *timerNow = [_DMLogDateFormatter stringFromDate:[NSDate date]];
        NSArray *timeArray = [timerNow componentsSeparatedByString:@":"];

        // 获取到时间
        float sec =  [timeArray[] intValue];
        float min =  [timeArray[] intValue] + sec / .f;
        float hour = [timeArray[] intValue] + min / .f;

        secondLayer.transform = \
            CATransform3DMakeRotation(DEGREES__TO__RADIANS(/.f)*sec + \
                                      DEGREES__TO__RADIANS(), \
                                      0.0, 0.0, 1.0);

        minuteLayer.transform = \
        CATransform3DMakeRotation(DEGREES__TO__RADIANS(/.f)*min + \
                                  DEGREES__TO__RADIANS(), \
                                  0.0, 0.0, 1.0);

        hourLayer.transform = \
        CATransform3DMakeRotation(DEGREES__TO__RADIANS(/.f)*hour + \
                                  DEGREES__TO__RADIANS(), \
                                  0.0, 0.0, 1.0);

        _timeLabel.text = [NSString stringWithFormat:@"%02d:%02d:%02d",
                           [timeArray[] intValue],
                           [timeArray[] intValue],
                           [timeArray[] intValue]];

    } timeInterval:NSEC_PER_SEC];
    [_timer start];
}

@end

RootViewController.m