iOS代码片段

1.播放视频

　　在单独页播放，使用以下方法

    MPMoviePlayerViewController *mpView = [[MPMoviePlayerViewController alloc] initWithContentURL:[NSURL URLWithString:VideoUrl]];
    mpView.moviePlayer.controlStyle = MPMovieControlStyleFullscreen;
    [mpView.moviePlayer play];
    [self presentMoviePlayerViewControllerAnimated:mpView];

　如果要在当前页播放，使用MPMoviePlayeController, 并将MPMoviePlayeController的view做为当前页的subview加入当前页面。

2.系统UI设置相关

　　隐藏状态栏（顶部20像素）

1 [[UIApplication sharedApplication] setStatusBarHidden:YES];

3. 页面跳转

1     //使用导航方式跳转到新的页面（页面由右侧滑如）
2     ViewController1 *viewController = [[ViewController1 alloc] init];
3     [self.navigationController pushViewController:viewController animated:YES];

1     //由导航出的新页面中返回（向右侧滑出）
2     [self.navigationController popViewControllerAnimated:YES];

1     //使用展示方式跳转到新页面（页面由底部滑入）
2     ViewController2 *viewController = [[ViewController2 alloc] init];
3     [self presentViewController:viewController animated:YES completion:^{}];

1     //由present的新页面中返回（向底部滑出）
2     [self dismissViewControllerAnimated:YES completion:^{ }];

4 UI控件

4.1 UIButton

    //viewDidLoad, 代码创建按钮
    UIButton *newViewBtn = [UIButton buttonWithType:UIButtonTypeRoundedRect];
    newViewBtn.frame = CGRectMake(10, 200, 100, 50);    
    [newViewBtn addTarget:self action:@selector(NavToViewClicked:) forControlEvents:UIControlEventTouchUpInside];
    [newViewBtn setTitle:@"Nav to View" forState:UIControlStateNormal];
    [self.view addSubview:newViewBtn];
    //*******************************************************************************

1 - (void)NavToViewClicked:(UIButton*)btn{
2     //使用导航方式跳转到新的页面（页面由右侧滑出）
3     ViewController1 *viewController = [[ViewController1 alloc] init];
4     [self.navigationController pushViewController:viewController animated:YES];
5 }

4.2导航栏

1     //AppDelegate - didFinishLaunchingWithOptions中，创建带导航栏的主页面
2     self.viewController = [[NavViewController alloc] init];
3     self.window.rootViewController = [[UINavigationController alloc] initWithRootViewController:self.viewController];

4.3 图片局部拉伸

1     // IOS 5.0之前
2     //图片将拉升左起50、上起60的像素。
3     UIImage *img = [UIImage imageNamed:@"girl.jpg"];
4     UIImage *bg = [img stretchableImageWithLeftCapWidth:50 topCapHeight:60];
5     UIImageView *imageView = [[UIImageView alloc] initWithFrame:CGRectMake(10, 10, 300, 400)];
6     //注意UIImageView的contendMode属性必须为UIViewContentModeScaleToFill。它也是默认值
7     //imageView.contentMode = UIViewContentModeScaleToFill;
8     imageView.image = bg;

1     // >= IOS 5.0的版本可用。
2     // 以下代码和使用stretchableImageWithLeftCapWidth作用相同。也可以用于拉升多个像素的区域
3     UIEdgeInsets set = UIEdgeInsetsMake(55, 14, 50, 45);
4     //car.jpg的尺寸为60*106
5     UIImage *bg = [[UIImage imageNamed:@"car.jpg"]resizableImageWithCapInsets:set];
6     UIImageView *imgView = [[UIImageView alloc] initWithFrame:CGRectMake(10, 10, 300, 400)];
7     imgView.image = bg;
8     [self.view addSubview:imgView];

1     //IOS6及之后版本，可以使用 resizableImageWithCapInsets
2     //以下代码用于平铺图片（纹理效果）
3     UIImage *bg = [[UIImage imageNamed:@"car.jpg"]resizableImageWithCapInsets:UIEdgeInsetsZero resizingMode:UIImageResizingModeTile];    
4     UIImageView *imgView = [[UIImageView alloc] initWithFrame:CGRectMake(10, 10, 300, 400)];
5     imgView.image = bg;
6     [self.view addSubview:imgView];

4.4 关闭屏幕键盘

1 //方法一：关闭键盘
2 [[[UIApplication sharedApplication] keyWindow] endEditing:YES];

 1 //方法二：关闭键盘
 2 [[self findFirstResponderBeneathView:self] resignFirstResponder];
 3 
 4 - (UIView*)findFirstResponderBeneathView:(UIView*)view
 5 {
 6     // Search recursively for first responder
 7     for ( UIView *childView in view.subviews ) {
 8         if ( [childView respondsToSelector:@selector(isFirstResponder)] && [childView isFirstResponder] )
 9             return childView;
10         UIView *result = [self findFirstResponderBeneathView:childView];
11         if ( result )
12             return result;
13     }
14     return nil;
15 }

1 // 将页面的主view创建为UIControl（它是UIView的子类）
2 // 这样就可一处理touchdown事件了
3 // 注意这个处理可能被其他UIControl（例如UIButton）屏蔽
4 self.view = [[UIControl alloc] init];
5 [(UIControl *)self.view addTarget:self action:@selector(pageTouchDown:) forControlEvents:UIControlEventTouchDown];
6 
7 - (void)pageTouchDown:(UIControl*)ctrl {
8     [[[UIApplication sharedApplication] keyWindow] endEditing:YES];
9 }

    //另外如果知道当前得到焦点的是哪个控件，可以直接执行
    [textField1 resignFirstResponder];

4.5 控件截图

 1 - (UIImage *)CaptureImage:(UIView *)subView
 2 {
 3     //支持retina高分的关键
 4     if(UIGraphicsBeginImageContextWithOptions != NULL)
 5     {
 6         UIGraphicsBeginImageContextWithOptions(subView.frame.size, NO, 0.0);
 7     } else {
 8         UIGraphicsBeginImageContext(subView.frame.size);
 9     }
10     
11     //获取图像
12     [subView.layer renderInContext:UIGraphicsGetCurrentContext()];
13     UIImage *image = UIGraphicsGetImageFromCurrentImageContext();
14     UIGraphicsEndImageContext();
15     
16     return image;
17 }

4.6 图片保存

 1 //保存图像至app目录
 2 - (void)SaveImageToAppDir:(UIImage *)image
 3 {
 4     NSString *path = [NSHomeDirectory() stringByAppendingFormat:@"/%ld.png", random()];
 5     if ([UIImagePNGRepresentation(image) writeToFile:path atomically:YES]) {
 6         NSLog(@"Succeeded! %@",path);
 7     }
 8     else {
 9         NSLog(@"Failed!");
10     }
11 }

 1 //保存图片至系统相册
 2 - (void)SaveImageToAlumb:(UIImage *)image
 3 {
 4     //保存过程中禁止用户操作
 5     [UIApplication sharedApplication].keyWindow.userInteractionEnabled = NO;
 6 
 7     UIImageWriteToSavedPhotosAlbum(image, self, @selector(imageSaved:didFinishSavingWithError:contextInfo:), nil);
 8 }
 9 
10 - (void)imageSaved:(UIImage *) image
11     didFinishSavingWithError: (NSError *) error
12                  contextInfo: (void *) contextInfo
13 {
14     //保存完毕后用户用户操作
15     [UIApplication sharedApplication].keyWindow.userInteractionEnabled = YES;
16     if (error)
17     {
18         NSLog(@"Save Image to Alumb Failed");
19         NSLog(@"%@", error.localizedFailureReason);
20     }
21     else
22     {
23         NSLog(@"Save Image to Alumb Sucessed");
24     }
25 }

4.7 返回图片数据

1 UIImage *image = ... 
2 //保存为jpg
3 CGFloat ratio = 0.7;
4 NSData *dataJpg = UIImageJPEGRepresentation(image, ratio);
5 
6 //保存为png
7 NSData *dataPng= UIImagePNGRepresentation(image);

5. 获取资源的路径、使用NSFileHandle操作文件、文件转码、webview控件设置透明

 1     NSString *path = [[NSBundle mainBundle] pathForResource:@"webViewContent" ofType:@"html"];
 2     NSFileHandle *readHandle = [NSFileHandle fileHandleForReadingAtPath:path];
 3             
 4     NSString *htmlString = [[NSString alloc] initWithData: 
 5                               [readHandle readDataToEndOfFile] encoding:NSUTF8StringEncoding];
 6     
 7     // to make html content transparent to its parent view -
 8     // 1) set the webview's backgroundColor property to [UIColor clearColor]
 9     // 2) use the content in the html: <body style="background-color: transparent">
10     // 3) opaque property set to NO
11     //
12     webView.opaque = NO;
13     webView.backgroundColor = [UIColor clearColor];
14     [self.webView loadHTMLString:htmlString baseURL:nil];
15     [htmlString release];

6. 时间函数相关操作。注意格式化是“yyyy”输出年数，“YYYY”输出本周所在年数。例如2012年最后两天所在的周算2013，所以这两天用YYYY格式化后输出2013

1     NSDate *myDate = [NSDate date];
2     NSTimeInterval secondsPerDay1 = 24*60*60;
3     NSDate *yesterDay = [myDate dateByAddingTimeInterval:-secondsPerDay1];

1     NSDateFormatter *formatter = [[NSDateFormatter alloc] init];
2     [formatter setDateFormat:@"yyyy-MM-dd HH:mm:ss"];
3     NSString *result = [formatter stringFromDate:yesterDay];

 1     //GMT时间转换为本地时间
 2     NSDateFormatter *gmtFormatter = [[NSDateFormatter alloc] init];
 3     [gmtFormatter setDateFormat:@"yyyy-MM-dd HH:mm:ss"];
 4     NSTimeZone *gmt = [NSTimeZone timeZoneWithAbbreviation:@"GMT"];
 5     [gmtFormatter setTimeZone:gmt];
 6     
 7     NSString *str = @"2013-06-20 14:20:30";
 8     //NSDate应该总是包含GMT时间（或者叫UTC时间）。
 9     NSDate *date1 = [gmtFormatter dateFromString:str];
10 
11     
12     NSDateFormatter *defaultFormatter = [[NSDateFormatter alloc] init];
13     [defaultFormatter setDateFormat:@"yyyy-MM-dd HH:mm:ss"];
14     //默认的设置中，NSDate将按当前时区转换为NSString
15     NSString *str2 = [defaultFormatter stringFromDate:date1];

7. 获取系统空闲内存、进程占用内存

 1 #import <mach/mach.h>
 2 // 获取当前设备可用内存(单位：MB）
 3 - (double)availableMemory
 4 {
 5     vm_statistics_data_t vmStats;
 6     mach_msg_type_number_t infoCount = HOST_VM_INFO_COUNT;
 7     kern_return_t kernReturn = host_statistics(mach_host_self(),
 8                                                HOST_VM_INFO,
 9                                                (host_info_t)&vmStats,
10                                                &infoCount);
11     
12     if (kernReturn != KERN_SUCCESS) {
13         return NSNotFound;
14     }
15     
16     return ((vm_page_size *vmStats.free_count) / 1024.0) / 1024.0;
17 }
18 
19 // 获取当前任务所占用的内存（单位：MB）
20 - (double)usedMemory
21 {
22     task_basic_info_data_t taskInfo;
23     mach_msg_type_number_t infoCount = TASK_BASIC_INFO_COUNT;
24     kern_return_t kernReturn = task_info(mach_task_self(),
25                                          TASK_BASIC_INFO,
26                                          (task_info_t)&taskInfo,
27                                          &infoCount);
28     
29     if (kernReturn != KERN_SUCCESS
30         ) {
31         return NSNotFound;
32     }
33     
34     return taskInfo.resident_size / 1024.0 / 1024.0;
35 }

8. alert 对话框使用

 1 -(IBAction)buttonChangeTime:(id)sender
 2 {
 3     NSString *msg = @"message content";
 4     //非ARC的代码需要手动release alert，或者设为autorelease
 5     UIAlertView *alert = [[UIAlertView alloc]
 6                           initWithTitle:@"button Pressed"
 7                           message:msg
 8                           delegate:self
 9                           cancelButtonTitle:@"确认"
10                           otherButtonTitles:@"我知道了", @"好的", nil];
11     [alert show];    
12 }
13 
14 #pragma mark alert delegate
15 - (void)alertView:(UIAlertView *)alertView clickedButtonAtIndex:(NSInteger)buttonIndex
16 {
17     NSLog(@"alertView button Index=%d", buttonIndex); //cancel button的index是0，其他从1累加
18 }

9.一些工程设置

　　9.1 在itunes中共享文件

　　- 打开[工程名]-Info.plist, 添加一条“Application supports iTunes file sharing” 并设为YES

　　- 也可以在project navigator（cmd+1）中选中工程 -> 右侧选中Targets下的项目名 -> 顶部选中info 　　-> 添加一行：“Application supports iTunes file sharing” 并设为YES

　　9.2 设置项目的url，（可以用“[appurl]:”的方式启动应用程序，同时可以传递参数)

　　- 在project navigator（cmd+1）中选中工程 -> 右侧选中Targets下的项目名 -> 顶部选中info -> 下方的URL Types中，URL Schemes中可以添加自定义的appurl。可以添加多个，用逗点分割

10. 文件路径及操作绘制

需要注意的是，下面这个方法取到的Documentation目录和itunes共享目录并不相同。前者是~/Library/Documentation, 后者是~/Documents

NSSearchPathForDirectoriesInDomains(NSDocumentationDirectory, NSUserDomainMask, YES)

1     //包中资源路径
2     //    /var/mobile/Applications/97499D0C-39B5-4BB4-B2B5-37D2475D5580/appName.app/Default.png
3     NSString *path1 = [[NSBundle mainBundle] pathForResource:@"Default" ofType:@"png"];
4     NSLog(@"path1=\n%@\n", path1);

1     //保存到根目录
2     //    /var/mobile/Applications/97499D0C-39B5-4BB4-B2B5-37D2475D5580/100.png
3     NSString *path2 = [NSHomeDirectory() stringByAppendingFormat:@"/%ld.png", 100];
4     NSLog(@"path2=\n%@\n", path2);

1     //路径展开
2     //    /var/mobile/Applications/97499D0C-39B5-4BB4-B2B5-37D2475D5580/astring.txt
3     NSString *path3 = [@"~/astring.txt" stringByExpandingTildeInPath];
4     NSLog(@"path3=\n%@\n", path3);

 1     //获取特定系统目录
 2     NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentationDirectory, NSUserDomainMask, YES);
 3     //    /var/mobile/Applications/97499D0C-39B5-4BB4-B2B5-37D2475D5580/Library/Documentation
 4     NSLog(@"dir=\n%@\n", paths[0]);
 5     
 6     //    /var/mobile/Applications/97499D0C-39B5-4BB4-B2B5-37D2475D5580/Library/Documentation/good/day
 7     NSString *path4 = [paths[0] stringByAppendingPathComponent:@"good/day"];
 8     NSLog(@"path4=\n%@\n", path4);
 9     
10     //    /var/mobile/Applications/97499D0C-39B5-4BB4-B2B5-37D2475D5580/Library/Documentation/good/day/1.txt
11     NSString *path5 = [path4 stringByAppendingPathComponent:@"1.txt"];
12     NSLog(@"path5=\n%@\n", path5);

 1     // 创建文件夹及文件
 2     NSData *data = [NSData data];
 3     NSFileManager *fm = [NSFileManager defaultManager];
 4     if (![fm createDirectoryAtPath:path4 withIntermediateDirectories:YES attributes:nil error:nil])
 5     {
 6         NSLog(@"create file fail");
 7     }
 8     NSError *err = [[NSError alloc] init];
 9     NSString *str = [NSString stringWithFormat:@"good text: %@ 不错啊", [NSDate date]];
10     if (![str writeToFile:path5 atomically:YES encoding:NSUTF8StringEncoding error:&err])
11     {
12         NSLog(@"error = %@", err);
13     }

11 网络相关

11.1 获取本地ip地址

 1 #include <ifaddrs.h>
 2 #include <arpa/inet.h>
 3 
 4 - (NSString *)getIPAddress
 5 {
 6     NSString *address = @"error";
 7     struct ifaddrs *interfaces = NULL;
 8     struct ifaddrs *temp_addr = NULL;
 9     int success = 0;
10     
11     //retrieve the current interfaces - returns 0 on success
12     success = getifaddrs(&interfaces);
13     if (success == 0) {
14         //Loop through linked list of interfaces
15         temp_addr = interfaces;
16         while (temp_addr != NULL) {
17             if (temp_addr->ifa_addr->sa_family == AF_INET) {
18                 //Check if interface is en0 which is the wifi connection on the iPhone
19                 if ([[NSString stringWithUTF8String: temp_addr->ifa_name] isEqualToString:@"en0"]) {
20                     //Get NSString from C String
21                     address =[NSString stringWithUTF8String:inet_ntoa(((struct sockaddr_in *) temp_addr->ifa_addr)->sin_addr)];
22                 }
23             }
24             temp_addr = temp_addr->ifa_next;
25         }
26     }
27     //Free memory
28     freeifaddrs(interfaces);
29     NSLog(@"addrees----%@",address);
30     return address;
31 }

12. 打印控件树

主线程任意地方调用 dumpViewTree

 1 - (void)dumpViewTree
 2 {
 3     UIView * rootView = [[[UIApplication sharedApplication] keyWindow] rootViewController].view;
 4     NSMutableArray * arr = [NSMutableArray array];
 5     [self _dumpView:rootView offset:0 result:arr];
 6     
 7     NSLog(@"\nAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA\n");
 8     
 9     NSMutableString * strResult = [NSMutableString string];
10     [strResult appendString:@"\n\n"];
11     for (NSString * str in arr)
12     {
13         [strResult appendFormat:@"%@\n", str];
14     }
15     NSLog(@"%@",strResult);
16     
17     NSLog(@"\nAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA\n");
18 }
19 
20 - (void)_dumpView:(UIView *)view offset:(NSUInteger)offset result:(NSMutableArray *)arrResult
21 {
22     id nextResp = [view nextResponder];
23     NSMutableString * str = [NSMutableString string];
24     
25     for (int i=0; i<offset; i++)
26     {
27         [str appendString:@"|   "];
28     }
29     if ([nextResp isKindOfClass:[UIViewController class]])
30     {
31         [str appendFormat:@"[%@] ", NSStringFromClass([nextResp class])];
32     }
33     
34     [str appendFormat:@"%@", view];
35     [arrResult addObject:str];
36     
37     for (UIView * subView in [view subviews])
38     {
39         [self _dumpView:subView offset:offset+1 result:arrResult];
40     }
41 }