常见的小知识

修改图片尺寸

    UIImage * image = nil;

    CGSize size = nil;

    UIGraphicsBeginImageContext(size);

    [image drawInRect:CGRectMake(0, 0, , size.width ,size.height)];

    UIImage * changedImage = UIGraphicsGetImageFromCurrentImageContext();

    UIGraphicsEndImageContext();

 

代码实现autoresizing

redView.autoresizingMask

 

 

CGRect CGRectInset ( CGRect rect, CGFloat dx, CGFloat dy );

以原来的rect为基础  改变宽和高  改变的幅度根据dx  dy来决定

两个视图的中心相同   只有大小不同

 

CGRect CGRectOffset( CGRect rect, CGFloat dx, CGFloat dy ); 

以原来的rect的左上角原点为基础   沿X轴Y轴进行移动    移动量根据dx和dy而定

ARC与MRC混编 BuildPhases>>ComplieSource>>     -fno-objc-arc

 

hidesBottomBarWhenPushed隐藏下方的tabbar

[UIApplication sharedApplication].keyWindow.rootViewController = mainViewController;设置主控制器

 调用代理方法时判断是否响应

if ([self respondsToSelector:]){     }

获取图片的大小

 NSStringFromCGSize(imge.size);

 

定义枚举类

/枚举 和宏定义相似

//(枚举的类型  枚举的名字)

//下载的过程中标题的切换

typedef NS_ENUM(NSInteger, ZYButtonState){

    //正常状态

    ZYButtonStateNomal  =0,

    //下载状态

    ZYButtonStateDownloading,

    //暂停状态

    ZYButtonStatePause,

    //完成状态

    ZYButtonStateComletion,

    

};

 

字符串NSString

NSString*string =@"sdfsfsfsAdfsdf";

string = [string substringToIndex:7];//截取掉下标7之后的字符串

NSLog(@"截取的值为：%@",string);

[string substringFromIndex:2];//截取掉下标2之前的字符串

NSLog(@"截取的值为：%@",string);

 

 

2.匹配字符串

NSString*string =@"sdfsfsfsAdfsdf";

NSRangerange = [stringrangeOfString:@"f"];//匹配得到的下标

NSLog(@"rang:%@",NSStringFromRange(range));

string = [string substringWithRange:range];//截取范围类的字符串

NSLog(@"截取的值为：%@",string);

 

 

3.分隔字符串

NSString*string =@"sdfsfsfsAdfsdf";

 

NSArray *array = [string componentsSeparatedByString:@"A"]; //从字符A中分隔成2个元素的数组

NSLog(@"array:%@",array); //结果是adfsfsfs和dfsdf

 

[字符串对象 stringByTrimmingCharactersInSet:[NSCharacterSet whitespaceAndNewlineCharacterSet]];  去空格和换行

  字符串分割

NSString *abc =@"1|2|3|4|5”;

 NSArray *arr =[abc componentsSeparatedByString:@"|”]

替换   把a替换为00

 [self stringByReplacingOccurrencesOfString:@“a" withString:@"00"];

NSString *urlString =[NSString stringWithFormat:@"http://apis.baidu.com/apistore/weatherservice/citylist?cityname=郑州&apikey=614ea11c21b05ee11ca45e2e1f44a711”];

字符串编码

 NSString *newString =[urlString stringByAddingPercentEscapesUsingEncoding:NSUTF8StringEncoding];

两个数组的第一个元素是否相同，如果相同，则返回 数组中，第一个元素的字符串，反之，返回null 对象

 

- (id)firstObjectCommonWithArray:(NSArray *)otherArray;

 

 *  计算文字尺寸

 *

 *  @param text    需要计算尺寸的文字

 *  @param font    文字的字体

 *  @param maxSize 文字的最大尺寸

 */

- (CGSize)sizeWithText:(NSString *)text font:(UIFont *)font maxSize:(CGSize)maxSize

{

    NSDictionary *attrs = @{NSFontAttributeName : font};

    return [text boundingRectWithSize:maxSize options:NSStringDrawingUsesLineFragmentOrigin attributes:attrs context:nil].size;

 

}

导航栏上的右键

UIBarButtonItem *rightItem =[[UIBarButtonItem alloc]initWithTitle:@"上传头像" style:UIBarButtonItemStylePlain target:self action:@selector(buttonAction)];        self.navigationItem.rightBarButtonItem =rightItem;

segmentedControl = [[UISegmentedControl alloc] initWithFrame:CGRectMake(100, 100, 200, 30)];

    [segmentedControl insertSegmentWithTitle:@"公共资源" atIndex:0 animated:YES];

    [segmentedControl insertSegmentWithTitle:@"个人资源" atIndex:1 animated:YES];

    segmentedControl.selectedSegmentIndex = 0;

    [segmentedControl addTarget:self action:@selector(switchOver:) forControlEvents:UIControlEventValueChanged];

    self.navigationItem.titleView = segmentedControl;

    UIButton * localFileButton = [[UIButton alloc] initWithFrame:CGRectMake(0, 0, 30, 30)];

    [localFileButton setImage:[UIImage imageNamed:@"download_button"] forState:UIControlStateNormal];

    [localFileButton addTarget:self action:@selector(localFileButtonClick) forControlEvents:UIControlEventTouchUpInside];

    UIBarButtonItem *rightItem =[[UIBarButtonItem alloc]initWithCustomView:localFileButton];

 

    self.navigationItem.rightBarButtonItem =rightItem;

 

创建图片选择器

UIImagePickerController * imgPicker = [[UIImagePickerController alloc] init];

    imgPicker.delegate = self;

    imgPicker.sourceType = UIImagePickerControllerSourceTypePhotoLibrary;

 

    imgPicker.allowsEditing = YES;

 

    [self presentViewController:imgPicker animated:YES completion:nil];

- (void)imagePickerController:(UIImagePickerController *)picker didFinishPickingImage:(UIImage *)image editingInfo:(NSDictionary *)editingInfo NS_DEPRECATED_IOS(2_0, 3_0)

{选中的图片

    NSMutableData * data = (NSMutableData *)UIImagePNGRepresentation(image);

    [self dismissViewControllerAnimated:YES completion:nil];

}

- (void)imagePickerController:(UIImagePickerController *)picker didFinishPickingMediaWithInfo:(NSDictionary *)info

{}

//取消

- (void)imagePickerControllerDidCancel:(UIImagePickerController *)picker

{

    [self dismissViewControllerAnimated:YES completion:nil];

}

设置scrollview的默认位置

    [_scrollView setContentOffset:CGPointMake(320*segmentedControl.selectedSegmentIndex,0) animated:YES];

写文件

NSFileManager *fm =[NSFileManager defaultManager];

    NSString *directoryPath =[NSHomeDirectory() stringByAppendingPathComponent:@"tmp/Downloads"];

    if (![fm fileExistsAtPath:directoryPath])

    {

        [fm createDirectoryAtPath:directoryPath withIntermediateDirectories:YES attributes:nil error:nil];下载时候有文件夹就够了    下载的时候会有加路径的代码

    }

    NSString *filePath =[NSHomeDirectory() stringByAppendingPathComponent:[NSString stringWithFormat:@"tmp/Downloads/%@",name]];

    if (![fm fileExistsAtPath:filePath])

    {

        [fm createFileAtPath:filePath contents:nil attributes:nil];文件写入本地需要创建到文件名

        

    }

清理NSUserDefaults

NSUserDefaults * user = [NSUserDefaults standardUserDefaults];

                        [user removeObjectForKey:@"token"];

                        [user removeObjectForKey:@"time"];

xib文件中有多个view时拖线连属性需要注意属性关联的对象

添加block块属性@property (nonatomic,copy) void(^block)(void);

调用块  self.block();      不谢void

ASI开启断点下载

配置asi

1.SystemConfiguration

2.CFNetwork

3.libz.1.2.5.dylib

4.MobileCoreServices

 

-(void)downLoadWithString:(NSString *)string name:(NSString *)name

{

    NSLog(@"下载开始");

    aRequest =[[ASIHTTPRequest alloc]initWithURL:[NSURL URLWithString:string]];

    aRequest.downloadProgressDelegate =self;

    NSString *documentsPath =[self getFilePathWithFileName:name];

    aRequest.downloadDestinationPath =documentsPath;

    NSString *temp =[self getTmpFilePathWithFileName:name];

    aRequest.temporaryFileDownloadPath=temp;

    aRequest.allowResumeForFileDownloads =YES;

    aRequest.delegate =self;

    [aRequest startAsynchronous];

}

- (void)requestFinished:(ASIHTTPRequest *)request

{

    NSLog(@"下载结束===");

    self.finishBlock();

}

- (void)setProgress:(float)newProgress

{

    NSLog(@"当前的进度---%f",newProgress);

    self.block(newProgress);

}

数组字典字符串数据源   之所以可以写入本地，是因为他们都实现了NSCoding协议

NSCoding协议规定了一套编码和解码的规范，只有实现NSCoding协议的对象才可以直接写入本地

base64EncodedString编码

base64DecodedString解码

拉伸图片

 LeftCap左边固定像素 topCap上固定像素   固定了图片左上角进行拉伸

 

UIImage * laShenImg = [img stretchableImageWithLeftCapWidth:23 topCapHeight:14];

 

 

 

越狱前后功能

沙盒前往  》  资源库     》Application Support      》   IPhone Simulator

iOS Device设备  真机测试

ARC需要关彻底

iOS手机端  不一样 

越狱之后才能根据SD卡查看

UISwitch点击后先改变自己的值再执行方法

NSArray * paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);

时间NSDate

判断时间

if ([date compare:expires]==NSOrderedDescending)

 {

   return NO;

  }

     a(newDate)   b(expriseDate)

     NSOrderedAscending  a<b

     NSOrderedSame,      a=b

     NSOrderedDescending a>b

时间格式

//先用第一个工具类初始化一个正常的date

    NSDateFormatter *iosForM =[[[NSDateFormatter alloc]init]autorelease];

    //设置成新浪返回的格式

    iosForM.dateFormat =@"EEE MMM dd HH:mm:ss Z yyyy";

    //如果不配置当前date的时区，是转换不成功的

    iosForM.locale =[[NSLocale alloc]initWithLocaleIdentifier:@"en_US"];

    //正常时间

    NSDate *date =[iosForM dateFromString:aString];

    

    //MM月dd日

    NSDateFormatter *fm =[[NSDateFormatter alloc]init];

    fm.dateFormat =@"MM月dd日 HH:mm:ss";

 

    return [fm stringFromDate:date];