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）

[[UIApplication sharedApplication] setStatusBarHidden:YES];

3. 页面跳转

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

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

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

    //由present的新页面中返回（向底部滑出）
    [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];
    //*******************************************************************************

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

4.2导航栏

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

4.3 图片局部拉伸

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

    // >= IOS 5.0的版本可用。
    // 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
    UIEdgeInsets set = UIEdgeInsetsMake(55, 14, 50, 45);
    //car.jpg的尺寸为60*106
    UIImage *bg = [[UIImage imageNamed:@"car.jpg"]resizableImageWithCapInsets:set];
    UIImageView *imgView = [[UIImageView alloc] initWithFrame:CGRectMake(10, 10, 300, 400)];
    imgView.image = bg;
    [self.view addSubview:imgView];

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

 4.4 关闭屏幕键盘

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

//方法二：关闭键盘
[[self findFirstResponderBeneathView:self] resignFirstResponder];

- (UIView*)findFirstResponderBeneathView:(UIView*)view
{
    // Search recursively for first responder
    for ( UIView *childView in view.subviews ) {
        if ( [childView respondsToSelector:@selector(isFirstResponder)] && [childView isFirstResponder] )
            return childView;
        UIView *result = [self findFirstResponderBeneathView:childView];
        if ( result )
            return result;
    }
    return nil;
}

// 将页面的主view创建为UIControl（它是UIView的子类）
// 这样就可一处理touchdown事件了
// 注意这个处理可能被其他UIControl（例如UIButton）屏蔽
self.view = [[UIControl alloc] init];
[(UIControl *)self.view addTarget:self action:@selector(pageTouchDown:) forControlEvents:UIControlEventTouchDown];

- (void)pageTouchDown:(UIControl*)ctrl {
    [[[UIApplication sharedApplication] keyWindow] endEditing:YES];
}

    //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

- (UIImage *)CaptureImage:(UIView *)subView
{
    //支持retina高分的关键
    if(UIGraphicsBeginImageContextWithOptions != NULL)
    {
        UIGraphicsBeginImageContextWithOptions(subView.frame.size, NO, 0.0);
    } else {
        UIGraphicsBeginImageContext(subView.frame.size);
    }
    
    //获取图像
    [subView.layer renderInContext:UIGraphicsGetCurrentContext()];
    UIImage *image = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();
    
    return image;
}

4.6 图片保存

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

//保存图片至系统相册
- (void)SaveImageToAlumb:(UIImage *)image
{
    //保存过程中禁止用户操作
    [UIApplication sharedApplication].keyWindow.userInteractionEnabled = NO;

    UIImageWriteToSavedPhotosAlbum(image, self, @selector(imageSaved:didFinishSavingWithError:contextInfo:), nil);
}

- (void)imageSaved:(UIImage *) image
    didFinishSavingWithError: (NSError *) error
                 contextInfo: (void *) contextInfo
{
    //保存完毕后用户用户操作
    [UIApplication sharedApplication].keyWindow.userInteractionEnabled = YES;
    if (error)
    {
        NSLog(@"Save Image to Alumb Failed");
        NSLog(@"%@", error.localizedFailureReason);
    }
    else
    {
        NSLog(@"Save Image to Alumb Sucessed");
    }
}

4.7 返回图片数据

UIImage *image = ... 
//保存为jpg
CGFloat ratio = 0.7;
NSData *dataJpg = UIImageJPEGRepresentation(image, ratio);

//保存为png
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

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

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

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

    //GMT时间转换为本地时间
    NSDateFormatter *gmtFormatter = [[NSDateFormatter alloc] init];
    [gmtFormatter setDateFormat:@"yyyy-MM-dd HH:mm:ss"];
    NSTimeZone *gmt = [NSTimeZone timeZoneWithAbbreviation:@"GMT"];
    [gmtFormatter setTimeZone:gmt];
    
    NSString *str = @"2013-06-20 14:20:30";
    //NSDate应该总是包含GMT时间（或者叫UTC时间）。
    NSDate *date1 = [gmtFormatter dateFromString:str];

    
    NSDateFormatter *defaultFormatter = [[NSDateFormatter alloc] init];
    [defaultFormatter setDateFormat:@"yyyy-MM-dd HH:mm:ss"];
    //默认的设置中，NSDate将按当前时区转换为NSString
    NSString *str2 = [defaultFormatter stringFromDate:date1];

7. 获取系统空闲内存、进程占用内存

#import <mach/mach.h>
// 获取当前设备可用内存(单位：MB）
- (double)availableMemory
{
    vm_statistics_data_t vmStats;
    mach_msg_type_number_t infoCount = HOST_VM_INFO_COUNT;
    kern_return_t kernReturn = host_statistics(mach_host_self(),
                                               HOST_VM_INFO,
                                               (host_info_t)&vmStats,
                                               &infoCount);
    
    if (kernReturn != KERN_SUCCESS) {
        return NSNotFound;
    }
    
    return ((vm_page_size *vmStats.free_count) / 1024.0) / 1024.0;
}

// 获取当前任务所占用的内存（单位：MB）
- (double)usedMemory
{
    task_basic_info_data_t taskInfo;
    mach_msg_type_number_t infoCount = TASK_BASIC_INFO_COUNT;
    kern_return_t kernReturn = task_info(mach_task_self(),
                                         TASK_BASIC_INFO,
                                         (task_info_t)&taskInfo,
                                         &infoCount);
    
    if (kernReturn != KERN_SUCCESS
        ) {
        return NSNotFound;
    }
    
    return taskInfo.resident_size / 1024.0 / 1024.0;
}

8. alert 对话框使用

-(IBAction)buttonChangeTime:(id)sender
{
    NSString *msg = @"message content";
    //非ARC的代码需要手动release alert，或者设为autorelease
    UIAlertView *alert = [[UIAlertView alloc]
                          initWithTitle:@"button Pressed"
                          message:msg
                          delegate:self
                          cancelButtonTitle:@"确认"
                          otherButtonTitles:@"我知道了", @"好的", nil];
    [alert show];    
}

#pragma mark alert delegate
- (void)alertView:(UIAlertView *)alertView clickedButtonAtIndex:(NSInteger)buttonIndex
{
    NSLog(@"alertView button Index=%d", buttonIndex); //cancel button的index是0，其他从1累加
}

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)

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

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

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

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

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

 11 网络相关

11.1 获取本地ip地址

#include <ifaddrs.h>
#include <arpa/inet.h>

- (NSString *)getIPAddress
{
    NSString *address = @"error";
    struct ifaddrs *interfaces = NULL;
    struct ifaddrs *temp_addr = NULL;
    int success = 0;
    
    //retrieve the current interfaces - returns 0 on success
    success = getifaddrs(&interfaces);
    if (success == 0) {
        //Loop through linked list of interfaces
        temp_addr = interfaces;
        while (temp_addr != NULL) {
            if (temp_addr->ifa_addr->sa_family == AF_INET) {
                //Check if interface is en0 which is the wifi connection on the iPhone
                if ([[NSString stringWithUTF8String: temp_addr->ifa_name] isEqualToString:@"en0"]) {
                    //Get NSString from C String
                    address =[NSString stringWithUTF8String:inet_ntoa(((struct sockaddr_in *) temp_addr->ifa_addr)->sin_addr)];
                }
            }
            temp_addr = temp_addr->ifa_next;
        }
    }
    //Free memory
    freeifaddrs(interfaces);
    NSLog(@"addrees----%@",address);
    return address;
}

 12. 打印控件树

主线程任意地方调用  dumpViewTree

- (void)dumpViewTree
{
    UIView * rootView = [[[UIApplication sharedApplication] keyWindow] rootViewController].view;
    NSMutableArray * arr = [NSMutableArray array];
    [self _dumpView:rootView offset:0 result:arr];
    
    NSLog(@"\nAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA\n");
    
    NSMutableString * strResult = [NSMutableString string];
    [strResult appendString:@"\n\n"];
    for (NSString * str in arr)
    {
        [strResult appendFormat:@"%@\n", str];
    }
    NSLog(@"%@",strResult);
    
    NSLog(@"\nAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA\n");
}

- (void)_dumpView:(UIView *)view offset:(NSUInteger)offset result:(NSMutableArray *)arrResult
{
    id nextResp = [view nextResponder];
    NSMutableString * str = [NSMutableString string];
    
    for (int i=0; i<offset; i++)
    {
        [str appendString:@"|   "];
    }
    if ([nextResp isKindOfClass:[UIViewController class]])
    {
        [str appendFormat:@"[%@] ", NSStringFromClass([nextResp class])];
    }
    
    [str appendFormat:@"%@", view];
    [arrResult addObject:str];
    
    for (UIView * subView in [view subviews])
    {
        [self _dumpView:subView offset:offset+1 result:arrResult];
    }
}