声明：原文地址：http://mobile.51cto.com/iphone-387111.htm

本文介绍了一些实际开发过程中的简单的小功能代码，也可以说是iOS开发中一些实用小代码。本人在前人整理的基础上补充了一点

下面开始按功能介绍iOS开发中一些实用小代码。

1.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]; 
} 

2.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; 
} 

3.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); 
} 

4.给imageView加载图片

UIImage *myImage = [UIImage imageNamed:@"1.jpg"]; 
[imageView setImage:myImage]; 
[self.view addSubview:imageView]; 

5.对图库的操作

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]; 
} 

6.跳到下个View

nextWebView = [[WEBViewController alloc] initWithNibName:@"WEBViewController" bundle:nil]; 
[self presentModalViewController:nextWebView animated:YES]; 

注意： 对于有navigation导航栏的跳转方式，可以用[self.navigationController pushViewController:[[SecondViewController alloc]init] animated:YES]; 参看：UINavigation的一些常用用法

7.创建一个UIBarButton右边按钮

UIBarButtonItem *rightButton = [[UIBarButtonItem alloc] initWithTitle:@"右边" style:UIBarButtonItemStyleDone target:self action:@selector(clickRightButton)]; 
[self.navigationItem setRightBarButtonItem:rightButton];  

8.设置navigationBar隐藏

self.navigationController.navigationBarHidden = YES;// 

9.设置bottombar隐藏【补充】

页面跳转后消失，返回上级页面出现：

 -(BOOL)hidesBottomBarWhenPushed 
{ 
return YES; 
}

注意： -(BOOL)hidesBottomBarWhenPushed
{
return YES;
}
改成：
self.navigationController.hidesBottomBarWhenPushed = YES;
则，底部bottombar无论如何也不会消失
若改成：
self.tabBarController.tabBar.hidden = YES;
则，底部bottombar将在页面跳转后永远消失，即使返回上级页面也不会出现

10.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; 

补充： 详细参看：UILabel中文本排布的一些常见写法

11.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]; 

12.让某个控件在View的中心位置显示：

label.center = self.view.center；//（某个控件，比如label，View） 

13.自定义cell中text各种效果：

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; 

14.隐藏statusBar：

在程序的viewDidLoad中加入

[[UIApplication sharedApplication]setStatusBarHidden:YES animated:NO]; 

15.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]; 

16.键盘透明：

textField.keyboardAppearance = UIKeyboardAppearanceAlert; 

17.状态栏的网络活动风火轮是否旋转：

[UIApplication sharedApplication].networkActivityIndicatorVisible = YES ; //默认值是NO。 

18.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); 

19.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; 

20.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]; 

21.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:80.f height:240.f]; 
UIImageView *imageView = [[UIImageView alloc]initWithImage:newImage]; 
[newImagerelease]; 
[image release]; 
[self.view addSubview:imageView]; 

22.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]; 

23.键盘回收：

-（IBAction）textFieldDoneEditing：（id）sender{ 
      [sender resighFirstRespond]； 
} 

通过点击背景回收键盘：（两个都得添加）

-（IBAction）textFieldDoneEditing：（id）sender{ 
[sender resighFirstRespond]； 
} 
-（IBAction）backgroundTapped：（id）sender{ 
[nameField resignFirstRespond]; 
[numberField resignFirstRespond]; 
} 

补充：详细参看：IOS点击键盘以外空白区域隐藏键盘的3种常见写法
#上面第九个和下面都是我补充的内容：

24.隐藏状态栏（电池，信号，运营商等）

在APPDelegate.m中添加

-(BOOL)prefersStatusBarHidden
{
	return YES;
}

25.禁止横屏

在APPDelegate.m中添加：

-(NSInteger)application:(UIApplication * )application supportedInterfaceOrientationsForWindow:(nullable UIWindow *)window
{
    return UIInterfaceOrientationMaskPortrait;
}

26设置启动界面停留时间

在APPDelegate.m中第一个方法中添加如下代码：

[NSThread sleepForTimeInterval:3];

注意：其中，sleepForTimeInterval:后面的参数单位是秒，数值大小大于0。
具体参看：IOS中如何设置启动界面的停留时间

27.URL encode编码和解码

+(NSString *)encodeString:(NSString *)unencodeString
{
    NSString * encodedString = (NSString *)CFBridgingRelease(CFURLCreateStringByAddingPercentEscapes(kCFAllocatorDefault, (CFStringRef)unencodeString, NULL, (CFStringRef)@"!*'();:@&=+$,/?%#[]", kCFStringEncodingUTF8));
    return unencodeString;
}

-(NSString *)decodeString:(NSString *)encodedString
{
    NSString * decodedString = (__bridge_transfer NSString *)CFURLCreateStringByReplacingPercentEscapesUsingEncoding(NULL, (__bridge CFStringRef)encodedString, CFSTR(""),CFStringConvertNSStringEncodingToEncoding(NSUTF8StringEncoding));
    return encodedString;
}

附：URL在线解析：UrlEncode编码/UrlDecode解码 - 站长工具