2016-2-20 周总结

//没有合理的计划让自己处于特别尴尬的境地,从现在开始要有合理的规划,每周的工作内容,每天的工作内容,每天及每周,每月的学习进度都要有一个清晰的计划.

一.block传值的使用.

1.现在有这样一个例子,需要将控制器b输入后的文字,传值到控制A的label上,如何用block实现?

//-----控制器b
//.h
typedef void (^ReturnText)(NSString *text);  //returnText是block的名称,text是传的参数

//定义block
@property (nonatomic,copy)ReturnText returnText;

//返回block方法
- (void)returnText:(ReturnText) returnText;

//.m

- (void)returnText:(ReturnText) returnText{

     self.returnText = returnText;
}

- (void)viewWillDisappear:(BOOL)animated{

    [super viewWillDisappear:animated];
   //设置block值

    if (self.returnText ){//不为空,就是控制器A需要调用它,否则此block为空
      self.retureText(text);
   }
}

//控制器A调用控制器b block
 控制器b *b = [[控制器b alloc] init];

    [b returnData:^(NSString *text) { //这段是关键代码,如果不调用它,block为空

       self.text = text;
    }];
       [self.navigationController pushViewController:b animated:YES];

二.相机与相册的使用及添加相册逻辑分析

1.1相机与相册的使用

//创建相机,相册
UIImagePickerController *cameraPc = [[UIImagePickerController alloc] init];

cameraPc.delegate = self;

cameraPc.sourceType = UIImagePickerControllerSourceTypeCamera;        //相机

cameraPc.sourceType = UIImagePickerControllerSourceTypePhotoLibrary; //相册

[self presentViewController:cameraPc animated:YES completion:nil];

1.2代理回调方法

需要导入#import <MobileCoreServices/MobileCoreServices.h>框架,在framwork添加并导入头文件

- (void)imagePickerController:(UIImagePickerController *)picker didFinishPickingMediaWithInfo:(NSDictionary<NSString *,id> *)info{

    [picker dismissViewControllerAnimated:YES completion:nil];

    NSString *mediaType = info[UIImagePickerControllerMediaType];

    UIImage *tempImg;

    if ([mediaType isEqualToString:(__bridge NSString *)kUTTypeImage]){  

        /* Let‘s get the metadata. This is only for

         images. Not videos */

        NSDictionary *metadata = info[UIImagePickerControllerMediaMetadata];

        UIImage *theImage = info[UIImagePickerControllerOriginalImage];//原图//界面显示

        tempImg = theImage;

    }

    [self.imageArray addObject:tempImg];

    [self handleShowSelectionAndCameraPhotos];

}

三.键盘返回事件和textView设置placeHolder(隐蔽文字)

//设置隐蔽文字,思路是创建一个label,放在textView上,并设置enable为NO,当文字发生改变时,隐藏label,否则显示.

- (BOOL)textView:(UITextView *)textView shouldChangeTextInRange:(NSRange)range replacementText:(NSString *)text

{
    //because Done is \n,
    if ([text isEqualToString:@"\n"]) {
        [textView resignFirstResponder];
        if (!textView.text.length) {
            self.placeholderL.text = @"请描述您的问题";
        }else{
            self.placeholderL.text = @"";
        }
        return NO;
    }
    return YES;

}