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嘿，

刚刚开始进入 C4，到目前为止我的经验非常好。我现在正在复制使用相机示例拍摄照片，出于某种原因，当我按照教程 ( http://www.c4ios.com/tutorials/takingSnapshots ) 中的描述执行所有操作时，我收到以下错误： “'TakePhoto'没有可见的@interface声明选择器'listenFor：from Object：'”（Take Photo是我正在使用的文件）我想我必须在类定义中声明“imageWasCaptured”，但我没有知道什么？有什么建议么？

更新：这里是代码 https://github.com/susemiessner/Urban-Alphabets/tree/master/urbanAlphabets 或者只是简单地复制 了 TakePhoto.h

#import "C4CanvasController.h"

@interface TakePhoto : C4CanvasController

@end

拍照.m

    #import "TakePhoto.h"
    #define NavBarHeight 42
    #define TopBarFromTop 20

    @interface TakePhoto ()

    @end

    @implementation TakePhoto {
        //common variables
        UIColor *navBarColor;
        UIColor *buttonColor;
        UIColor *typeColor;

        //top toolbar
        C4Shape *topNavBar;
        C4Font *fatFont;
        C4Label *takePhoto;



        //camera
        C4Camera *cam;

        //bottom Toolbar
        C4Shape *bottomNavBar;
        C4Button *takePhotoButton;
    }
    -(void) setup{
        navBarColor=[UIColor colorWithRed:0.96875 green:0.96875 blue:0.96875 alpha:1];
        buttonColor= [UIColor colorWithRed:0.8984275 green:0.8984275 blue:0.8984275 alpha:1];
        typeColor=[UIColor colorWithRed:0.19921875 green:0.19921875 blue:0.19921875 alpha:1];

        [self topBarSetup];
        [self bottomBarSetup];
        [self cameraSetup];

    }
    -(void)topBarSetup{
        topNavBar=[C4Shape rect:CGRectMake(0, TopBarFromTop, self.canvas.width, NavBarHeight)];
        topNavBar.fillColor=navBarColor;
        topNavBar.lineWidth=0;
        [self.canvas addShape:topNavBar];


        fatFont=[C4Font fontWithName:@"HelveticaNeue-Bold" size:17];
        takePhoto = [C4Label labelWithText:@"Take Photo" font:fatFont];
        takePhoto.center=topNavBar.center;
        [self.canvas addLabel:takePhoto];}

    -(void)cameraSetup{
        cam = [C4Camera cameraWithFrame:CGRectMake(0,TopBarFromTop+NavBarHeight, self.canvas.width, self.canvas.height-(2*NavBarHeight+TopBarFromTop))];
        [self.canvas addCamera:cam];
        [cam initCapture];
        //tapping to take image
        [self addGesture:TAP name:@"capture" action:@"capturedImage"];
        [self numberOfTouchesRequired:1 forGesture:@"capture"];
//the following line is where I get the error
        [self listenFor:@"imageWasCaptured" fromObject:@"putCapturedImageOnCanvas"];
    }
    -(void) bottomBarSetup{
        bottomNavBar=[C4Shape rect:CGRectMake(0, self.canvas.height-(NavBarHeight), self.canvas.width, NavBarHeight)];
        bottomNavBar.fillColor= navBarColor;
        bottomNavBar.lineWidth=0;
        [self.canvas addShape:bottomNavBar];

        takePhotoButton=[UIButton buttonWithType: ROUNDEDRECT];
        [takePhotoButton setTitle:@"TakePhoto" forState:UIControlStateNormal];
        takePhotoButton.frame=CGRectMake(self.canvas.width/2-50, self.canvas.height-(NavBarHeight), 100, NavBarHeight);
        takePhotoButton.backgroundColor=buttonColor;
        takePhotoButton.tintColor=typeColor;
        [self.canvas addSubview:takePhotoButton];

    }

    -(void) takingPhoto{
        [cam captureImage];
    }
    -(void) captureImage{
        [cam captureImage];
    }
    -(void)putCapturedImageOnCanvas{
        C4Image *img = cam.capturedImage;
        img.width=240;
        img.center=CGPointMake(self.canvas.width*2/3, self.canvas.center.y);

    }


    @end
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1 回答 1

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为了让你的概念发挥作用，你的方法中有几个漏洞会阻止你看到任何实际发生的事情。你的问题绝对是其中之一。

要回答您的问题：

listenFor:fromObject:无法识别，因为它实际上不存在。

方法的目的listenFor是让您的应用程序或特定对象可以对应用程序中其他地方发生的通知或操作做出反应。因此，您要做的是在发生某些事情时运行一个方法。

你的方法应该是：

[self listenFor:@"imageWasCaptured" fromObject:cam andRunMethod:@"methodName"];

你想听听相机何时完成拍摄，然后用它做一些事情......

我注意到的其他事情...

如果要使用 a C4Button，则执行以下操作：

takePhotoButton=[UIButton buttonWithType: ROUNDEDRECT];
[takePhotoButton setTitle:@"TakePhoto" forState:UIControlStateNormal];

应该：

takePhotoButton = [C4Button buttonWithType:ROUNDEDRECT];
[takePhotoButton setTitle:@"TakePhoto" forState:NORMAL];

此外，您正在继承C4CanvasController. 要将TakePhoto对象的视图放到主画布上，您需要正确创建它。

为了在主画布中执行此操作，我在我的工作区中编写了以下内容：

#import "C4Workspace.h"
#import "TakePhoto.h"

@implementation C4WorkSpace {
    TakePhoto *tp;
}

-(void)setup {
    tp = [TakePhoto new];
    tp.canvas.frame = CGRectMake(30,
                                 30,
                                 self.canvas.width - 60,
                                 self.canvas.height - 60);
    tp.canvas.shadowOffset = CGSizeMake(10,10);
    tp.canvas.shadowOpacity = 1.0f;
    tp.canvas.userInteractionEnabled = YES;
    [tp setup];
    tp.mainCanvas = self.canvas;
    [self.canvas addSubview:tp.canvas];
}
@end

最后，为了将你的相机图像放到主画布上，我不得不做一些桥接。我在其中创建了一个属性TakePhoto，可让我在新控制器中设置主画布。您会在上面的代码行中注意到tp.mainCanvas = self.canvas...

标题TakePhoto现在看起来像：

#import "C4CanvasController.h"

@interface TakePhoto : C4CanvasController
@property (readwrite, strong) C4Window *mainCanvas;
@end

该putImageOnCanvas方法现在看起来像：

-(void)putCapturedImageOnCanvas{
    C4Image *img = cam.capturedImage;
    img.width=240;
//    img.center=CGPointMake(self.canvas.width*2/3, self.canvas.center.y);
    img.center = CGPointMake([C4Math randomInt:self.mainCanvas.width], [C4Math randomInt:self.mainCanvas.height]);
    [self.mainCanvas addImage:img];
    [self.mainCanvas bringSubviewToFront:self.canvas];
}

最后两行将图像放在画布上，然后确保TakePhoto画布（即带有相机的画布）被带到前景，因此新添加的图像不会遮挡它。

因为您正在使用C4CanvasController您的应用程序结构的子类，所以看起来像：

C4WorkSpace.canvas > TakePhoto.canvas > Camera

于 2013-10-17T17:38:56.837 回答