iOS 有用的代码片段

12.判断邮箱格式是否正确的代码：
//利用正则表达式验证
-(BOOL)isValidateEmail:(NSString *)email
{
NSString *emailRegex = @"[A-Z0-9a-z._%+-]+@[A-Za-z0-9.-]+\\.[A-Za-z]{2,4}";
NSPredicate *emailTest = [NSPredicate predicateWithFormat:@"SELF MATCHES%@",emailRegex];
return [emailTest evaluateWithObject:email];
}
13.图片压缩
用法：UIImage *yourImage= [self imageWithImageSimple:image scaledToSize:CGSizeMake(210.0, 210.0)];
//压缩图片
- (UIImage*)imageWithImageSimple:(UIImage*)image scaledToSize:(CGSize)newSize
{
// Create a graphics image context
UIGraphicsBeginImageContext(newSize);
// Tell the old image to draw in this newcontext, with the desired
// new size
[image drawInRect:CGRectMake(0,0,newSize.width,newSize.height)];
// Get the new image from the context
UIImage* newImage = UIGraphicsGetImageFromCurrentImageContext();
// End the context
UIGraphicsEndImageContext();
// Return the new image.
return newImage;
}
14.亲测可用的图片上传代码
- (IBAction)uploadButton:(id)sender {
UIImage *image = [UIImage imageNamed:@"1.jpg"]; //图片名
NSData *imageData = UIImageJPEGRepresentation(image,0.5);//压缩比例
NSLog(@"字节数:%i",[imageData length]);
// post url
NSString *urlString = @"http://192.168.1.113:8090/text/UploadServlet";
//服务器地址
// setting up the request object now
NSMutableURLRequest *request = [[NSMutableURLRequest alloc] init] ;
[request setURL:[NSURL URLWithString:urlString]];
[request setHTTPMethod:@"POST"];
//
NSString *boundary = [NSString stringWithString:@"---------------------------14737809831466499882746641449"];
NSString *contentType = [NSString stringWithFormat:@"multipart/form-data;boundary=%@",boundary];
[request addValue:contentType forHTTPHeaderField: @"Content-Type"];
//
NSMutableData *body = [NSMutableData data];
[body appendData:[[NSString stringWithFormat:@"\r\n--%@\r\n",boundary] dataUsingEncoding:NSUTF8StringEncoding]];
[body appendData:[[NSString stringWithString:@"Content-Disposition:form-data; name=\"userfile\"; filename=\"2.png\"\r\n"] dataUsingEncoding:NSUTF8StringEncoding]]; //上传上去的图片名字
[body appendData:[[NSString stringWithString:@"Content-Type: application/octet-stream\r\n\r\n"] dataUsingEncoding:NSUTF8StringEncoding]];
[body appendData:[NSData dataWithData:imageData]];
[body appendData:[[NSString stringWithFormat:@"\r\n--%@--\r\n",boundary] dataUsingEncoding:NSUTF8StringEncoding]];
  [request setHTTPBody:body];
// NSLog(@"1-body:%@",body);
NSLog(@"2-request:%@",request);
NSData *returnData = [NSURLConnection sendSynchronousRequest:request returningResponse:nil error:nil];
NSString *returnString = [[NSString alloc] initWithData:returnData encoding:NSUTF8StringEncoding];
NSLog(@"3-测试输出：%@",returnString);
15.给imageView加载图片
UIImage *myImage = [UIImage imageNamed:@"1.jpg"];
   [imageView setImage:myImage];
   [self.view addSubview:imageView];
16.对图库的操作
选择相册：
UIImagePickerControllerSourceTypesourceType=UIImagePickerControllerSourceTypeCamera;
   if (![UIImagePickerControllerisSourceTypeAvailable:UIImagePickerControllerSourceTypeCamera]) {
       sourceType=UIImagePickerControllerSourceTypePhotoLibrary;
   }
   UIImagePickerController * picker = [[UIImagePickerControlleralloc]init];
   picker.delegate = self;
   picker.allowsEditing=YES;
   picker.sourceType=sourceType;
   [self presentModalViewController:picker animated:YES];
选择完毕：
 -(void)imagePickerController:(UIImagePickerController*)pickerdidFinishPickingMediaWithInfo:(NSDictionary *)info
{
   [picker dismissModalViewControllerAnimated:YES];
   UIImage * image=[info objectForKey:UIImagePickerControllerEditedImage];
   [self performSelector:@selector(selectPic:) withObject:imageafterDelay:0.1];
}
 -(void)selectPic:(UIImage*)image
{
   NSLog(@"image%@",image); 
   imageView = [[UIImageView alloc] initWithImage:image];
   imageView.frame = CGRectMake(0, 0, image.size.width, image.size.height);
[self.viewaddSubview:imageView];
   [self performSelectorInBackground:@selector(detect:) withObject:nil];
}
detect为自己定义的方法，编辑选取照片后要实现的效果
取消选择：
 -(void)imagePickerControllerDIdCancel:(UIImagePickerController*)picker
{
   [picker dismissModalViewControllerAnimated:YES];
}
17.跳到下个View
nextWebView = [[WEBViewController alloc] initWithNibName:@"WEBViewController" bundle:nil];
[self presentModalViewController:nextWebView animated:YES];


//创建一个UIBarButtonItem右边按钮
UIBarButtonItem *rightButton = [[UIBarButtonItem alloc] initWithTitle:@"右边" style:UIBarButtonItemStyleDone target:self action:@selector(clickRightButton)];
[self.navigationItem setRightBarButtonItem:rightButton];
设置navigationBar隐藏
self.navigationController.navigationBarHidden = YES;//
iOS开发之UIlabel多行文字自动换行 （自动折行）
UIView *footerView = [[UIView alloc]initWithFrame:CGRectMake(10, 100, 300, 180)];
UILabel *label = [[UILabel alloc]initWithFrame:CGRectMake(10, 100, 300, 150)];
label.text = @"Hello world! Hello world!Hello world! Hello world! Hello world! Hello world! Hello world! Hello world!Hello world! Hello world! Hello world! Hello world! Hello world! Helloworld!";
//背景颜色为红色
label.backgroundColor = [UIColor redColor];
//设置字体颜色为白色
label.textColor = [UIColor whiteColor];
//文字居中显示
label.textAlignment = UITextAlignmentCenter;
//自动折行设置
label.lineBreakMode = UILineBreakModeWordWrap;
label.numberOfLines = 0;
30.代码生成button
CGRect frame = CGRectMake(0, 400, 72.0, 37.0);
UIButton *button = [UIButton buttonWithType:UIButtonTypeRoundedRect];
button.frame = frame;
[button setTitle:@"新添加的按钮" forState: UIControlStateNormal];
button.backgroundColor = [UIColor clearColor];
button.tag = 2000;
[button addTarget:self action:@selector(buttonClicked:) forControlEvents:UIControlEventTouchUpInside];
[self.view addSubview:button];
31.让某个控件在View的中心位置显示：
（某个控件，比如label，View）label.center = self.view.center;
32.好看的文字处理
以tableView中cell的textLabel为例子：
cell.backgroundColor = [UIColorscrollViewTexturedBackgroundColor];
//设置文字的字体
cell.textLabel.font = [UIFont fontWithName:@"AmericanTypewriter" size:100.0f];
//设置文字的颜色
cell.textLabel.textColor = [UIColor orangeColor];
//设置文字的背景颜色
cell.textLabel.shadowColor = [UIColor whiteColor];
//设置文字的显示位置
cell.textLabel.textAlignment = UITextAlignmentCenter;
33. ———————-隐藏Status Bar—————————–
读者可能知道一个简易的方法,那就是在程序的viewDidLoad中加入
[[UIApplication sharedApplication]setStatusBarHidden:YES animated:NO];
33. 更改AlertView背景 

UIAlertView *theAlert = [[[UIAlertViewalloc] initWithTitle:@"Atention"
                                                     message: @"I'm a Chinese!"
                                                    delegate:nil 
                                            cancelButtonTitle:@"Cancel" 
                                            otherButtonTitles:@"Okay",nil] autorelease];
   [theAlert show];
   UIImage *theImage = [UIImageimageNamed:@"loveChina.png"];   
   theImage = [theImage stretchableImageWithLeftCapWidth:0topCapHeight:0];
   CGSize theSize = [theAlert frame].size;
    UIGraphicsBeginImageContext(theSize);    
   [theImage drawInRect:CGRectMake(5, 5, theSize.width-10, theSize.height-20)];//这个地方的大小要自己调整，以适应alertview的背景颜色的大小。
   theImage = UIGraphicsGetImageFromCurrentImageContext();   
UIGraphicsEndImageContext();
   theAlert.layer.contents = (id)[theImage CGImage];
34. 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。

35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(200,400)); 

//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 = UIImagePNGRepresentation(aImage);
36更改cell选中的背景
    UIView *myview = [[UIView alloc] init];
    myview.frame = CGRectMake(0, 0, 320, 47);
    myview.backgroundColor = [UIColorcolorWithPatternImage:[UIImage imageNamed:@"0006.png"]];
    cell.selectedBackgroundView = myview; 
37显示图像:
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];
38.能让图片适应框的大小（没有确认）
NSString*imagePath = [[NSBundle mainBundle] pathForResource:@"XcodeCrash"ofType:@"png"];    
    UIImage *image = [[UIImage alloc]initWithContentsOfFile:imagePath];
       UIImage *newImage= [image transformWidth:80.f height:240.f];
    UIImageView *imageView = [[UIImageView alloc]initWithImage:newImage];
        [newImagerelease];
    [image release];
    [self.view addSubview:imageView];
39.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(0, 0, 120, 120)];
[imgButton setBackgroundImage:(UIImage *)[self.imgArray objectAtIndex:indexPath.row] forState:UIControlStateNormal];
imgButton.tag=[indexPath row];
[imgButton addTarget:self action:@selector(buttonClick:) forControlEvents:UIControlEventTouchUpInside]; 

 原文： http://www.cocoachina.com/bbs/read.php?tid=108916&fpage=2