使用 UISlider 更改 CALayer 值

Question

希望有人可以帮助解决这个问题。我正在尝试使用 UISlider 更改 CA 子层中的值。已经研究了几天，但似乎无法弄清楚。相机运行良好，滑块在移动，但连接在某处丢失..！

附言。对此相对较新，因此将不胜感激：-)

谢谢！

.h 文件：

#import <UIKit/UIKit.h>
#import <AVFoundation/AVFoundation.h>
#import <QuartzCore/QuartzCore.h>

@interface AVViewController : UIViewController{
IBOutlet UISlider *mySlider;
}

@property (nonatomic, retain) IBOutlet UISlider*mySlider;

- (IBAction)adjustValue:(id)sender;
@end

来自@implementation 行的.m 文件：

@implementation AVViewController

@synthesize mySlider;

- (IBAction)adjustValue:(UISlider *)sender {
float value = [(UISlider *)sender value];
if (value <0) value = 0;
if (value >0) value = 1;
mySlider.value = value;
}

- (void)viewDidLoad
{
[super viewDidLoad];

AVCaptureSession *session = [[AVCaptureSession alloc] init];
[session setSessionPreset:AVCaptureSessionPresetHigh];

NSArray *devices = [AVCaptureDevice devicesWithMediaType:AVMediaTypeVideo];
    AVCaptureDevice *frontCamera = nil;
    for (AVCaptureDevice *device in devices) {
        if (device.position == AVCaptureDevicePositionFront) {
            frontCamera = device;
            break;
        } 
}

NSError *error = nil;    
AVCaptureDevice *input = [AVCaptureDeviceInput deviceInputWithDevice:frontCamera error:&error];
    [session addInput:input];

AVCaptureVideoPreviewLayer *previewLayer = [[AVCaptureVideoPreviewLayer alloc] initWithSession:session];
[previewLayer setVideoGravity:AVLayerVideoGravityResizeAspectFill];

CALayer *rootLayer = [[self view] layer];
[rootLayer setMasksToBounds:YES];
[previewLayer setFrame:CGRectMake(15, 15, 290 , 350)];
previewLayer.cornerRadius = 100.0;
[rootLayer insertSublayer:previewLayer atIndex:0];

CALayer *sublayer = [CALayer layer];
sublayer.frame = CGRectMake (15,15,previewLayer.bounds.size.width,previewLayer.bounds.size.height);
//VALUES TO BE ADJUSTED WITH UI SLIDER
sublayer.backgroundColor = [UIColor colorWithRed:0.0 green:0.0 blue:0.0 alpha:mySlider.value].CGColor;
[self.view.layer addSublayer:sublayer];

[session startRunning];

}

Answer 1

• 您需要将滑块的值更改事件连接到您的 IBAction。
• 您还需要将实例保存到您的子层，以便您可以从viewDidLoad 之外引用它。

在viewDidLoad 中添加：

   // Call adjustValue: when the slider value changes
   [slider addTarget:self action:@selector(adjustValue:) forControlEvents:UIControlEventValueChanged];

   // create and configure sub layer
   ...
   self.mysublayer = sublayer;

然后在IBAction你可以修改你的图层：

- (IBAction)adjustValue:(UISlider *)sender {
    float value = [sender value];
    // Modify layer here.
    self.mysublayer.backgroundColor = [UIColor colorWithRed:0.0 green:0.0 blue:0.0 alpha:value].CGColor;

}

希望这会有所帮助！