iOS小技巧

键盘透明:  

textField.keyboardAppearance = UIKeyboardAppearanceAlert;
状态栏的网络活动风火轮是否旋转:

[UIApplication sharedApplication].networkActivityIndicatorVisible , 默认值是 NO 。 
.截取屏幕图片:

// 创建一个基于位 图的图形上下文并指定大小为CGSizeMake(200,400)
UIGraphicsBeginImageContext(CGSizeMake(,)); //renderInContext 呈现接受者及其子范围到 指定的上下文
[self.view.layer renderInContext:UIGraphicsGetCurrentContext()];
// 返回 一个基于当前图形上下文的图片
UIImage *aImage = UIGraphicsGetImageFromCurrentImageContext();
// 移除栈顶 的基于当前位图的图形上下文
UIGraphicsEndImageContext();
// 以 png 格式 返回指定图片的数据
imageData = UIImagePNGR epresentation(aImage);
更改cell选中的背景: 

UIView *myview = [[UIView alloc] init];
myview.frame = CGRectMake(, , , );
myview.backgroundColor = [UIColorcolorWithPatternImage:[UIImage imageNamed:@"0006.png"]];
cell.selectedBackgroundView = myview;
.显示图片:

CGRect myImageRect = CGRectMake(0.0f, 0.0f, 320.0f, 109.0f);
UIImageView *myImage = [[UIImageView alloc] initWithFrame:myImageRect];
[myImage setImage:[UIImage imageNamed:@"myImage.png"]];
myImage.opaque = YES; //opaque 是否透明
[self.view addSubview:myImage];
能让图片适应框的大小(beta)

NSString*imagePath = [[NSBundle mainBundle] pathForResource:@"XcodeCrash"ofType:@"png"];
UIImage *image = [[UIImage alloc]initWithContentsOfFile:imagePath];
UIImage *newImage= [image transformWidth:.f height:.f];
UIImageView *imageView = [[UIImageView alloc]initWithImage: newImage];
[newImagerelease];
[image release];
[self.view addSubview:imageView];
  实现点击图片进行跳转的代码:(生成一个带有背景图片的button,给button绑定想要的事件)

UIButton *imgButton=[[UIButton alloc]initWithFrame:CGRectMake(, , , )];
[imgButton setBackgroundImage:(UIImage *)[self.imgArray objectAtIndex:indexPath.row] forState:UIControlStateNormal];
imgButton.tag=[indexPath row];
[imgButton addTarget:self action:@selector(buttonClick:) forControlEvents:UIControlEventTouchUpInside];
.第二种方法:在背景图片上添加Tap事件,相应单击处理。这种方法,很好代替了button方式,但是如果UI上没有背景图片,这种方法又回到到第一种山寨的方法行列中。

// 添加带有处理时间的背景图片 

UIImageView *backView = [[UIImageView alloc] initWithFrame:CGRectMake(, , self.view.bounds.size.width, self.view.bounds.size.height)];  

    backView.image = [UIImage imageNamed:@"small3.png"];  

    backView.userInteractionEnabled = YES;  

    UITapGestureRecognizer *singleTouch = [[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(dismissKeyboard:)];  

    [backView addGestureRecognizer:singleTouch];  

    backView.tag = ;  

    [self.view addSubview:backView];  

-(void)dismissKeyboard:(id)sender{  

    [text resignFirstResponder];  

}  
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