问只有在满足某些条件的情况下才使用长按压手势

EN

#import "ViewController.h"
#import <CoreMotion/CoreMotion.h>

@interface ViewController () {

    NSOperationQueue    *motionQueue;
    NSTimer             *touchTimer;
    NSTimeInterval      initialTimeStamp;
    BOOL                touchValid;

    float                timerPollInSeconds;
    float                longPressTimeRequired;
}

@property (strong, nonatomic)            NSTimer             *touchTimer;
@property (assign, nonatomic)            NSTimeInterval      initialTimeStamp;
@property (assign, nonatomic)            BOOL                touchValid;
@property (assign, nonatomic)            float               timerPollInSeconds;
@property (assign, nonatomic)            float               longPressTimeRequired;
@property (strong, nonatomic)            CMMotionManager     *motionManager;
@property (strong, nonatomic)            NSOperationQueue    *motionQueue;


@end

@implementation ViewController

@synthesize touchTimer = _touchTimer, initialTimeStamp, touchValid, motionQueue = _motionQueue;
@synthesize timerPollInSeconds, longPressTimeRequired, motionManager = _motionManager;

- (void)viewDidLoad
{
    self.timerPollInSeconds = 0.25f;
    self.longPressTimeRequired = 3.0f;
    self.touchTimer = nil;
    self.touchValid = NO;
    self.initialTimeStamp = NSTimeIntervalSince1970;
    self.motionManager = [[CMMotionManager alloc] init];
    self.motionQueue = [[NSOperationQueue alloc] init];
    [_motionQueue setName:@"MotionQueue"];
    [_motionQueue setMaxConcurrentOperationCount:NSOperationQueueDefaultMaxConcurrentOperationCount];

    [super viewDidLoad];

    self.view.multipleTouchEnabled = NO;
}

- (void)didReceiveMemoryWarning
{
    [super didReceiveMemoryWarning];
    // Dispose of any resources that can be recreated.
}

#pragma mark - Operations

-(void) startLongPressMonitorWithTimeStamp:(NSTimeInterval) timeStamp {
    NSLog(@"Starting monitoring - %g", timeStamp);
    if( self.touchTimer ) {
        if( [_touchTimer isValid] ) {
            [_touchTimer invalidate];
        }
    }

    self.touchTimer = [NSTimer timerWithTimeInterval:self.timerPollInSeconds target:self selector:@selector(timerPolled:) userInfo:nil repeats:YES];

    if( [_motionManager isAccelerometerAvailable] ) {
        NSLog(@"Accelerometer Available");
        if( ![_motionManager isAccelerometerActive] ) {
            NSLog(@"Starting Accelerometer");
            [_motionManager startAccelerometerUpdatesToQueue:self.motionQueue withHandler:^(CMAccelerometerData *accelerometerData, NSError *error) {

                if (ABS(accelerometerData.acceleration.x) < 0.3 && ABS(accelerometerData.acceleration.y) < 0.30 && ABS(accelerometerData.acceleration.z) > 0.70) // Phone is flat and screen faces up
                {
                    dispatch_sync(dispatch_get_main_queue(), ^{
                        self.touchValid = YES;
                    });
                }
                else
                {
                    dispatch_sync(dispatch_get_main_queue(), ^{
                        self.touchValid = NO;
                        [self stopLongPressMonitoring:YES];
                    });
                };
            }];
        }
        else {
            NSLog(@"Accelerometer already active");
        }
    }
    else {
        NSLog(@"Accelerometer not available");
    }

    self.initialTimeStamp = timeStamp;

    self.touchValid = YES;
    [_touchTimer fire];

    [[NSRunLoop mainRunLoop] addTimer:self.touchTimer forMode:NSRunLoopCommonModes];
}



-(void) stopLongPressMonitoring:(BOOL) touchSuccessful {
    [_motionManager stopAccelerometerUpdates];
    [_touchTimer invalidate];
    self.touchValid = NO;

    if( touchSuccessful ) {
        NSLog(@"Yes");
    }
    else {
         NSLog(@"No");
    }
}

#pragma mark - User Interaction
-(void) touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event {

    //We're using the current times, interval since the touches timestamp refers to system boot up
    // it is more than feasible to use this boot up time, but for simplicity, I'm just using this
    NSTimeInterval timestamp = [NSDate timeIntervalSinceReferenceDate];
    [self startLongPressMonitorWithTimeStamp:timestamp];
}

-(void) touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event {
    if( self.touchValid && [NSDate timeIntervalSinceReferenceDate] - self.initialTimeStamp == self.longPressTimeRequired ) {
        [self stopLongPressMonitoring:YES];
    }
    else {
        [self stopLongPressMonitoring:NO];
    }
}



#pragma mark - Timer Call back
-(void) timerPolled:(NSTimer *) timer {
    NSTimeInterval firedTimeStamp = [NSDate timeIntervalSinceReferenceDate];
    NSLog(@"Timer polled - %g", firedTimeStamp);
    if( self.touchValid ) {
        NSLog(@"Time elapsed: %d", (int)(firedTimeStamp - self.initialTimeStamp));

        if( firedTimeStamp - self.initialTimeStamp >= self.longPressTimeRequired ) {
            NSLog(@"Required time has elapsed");
            [self stopLongPressMonitoring:YES];
        }
    }
    else {
        NSLog(@"Touch invalidated");
        [self stopLongPressMonitoring:NO];
    }
}


@end