%c 一个单一的字符
%d 一个十进制整数
%i 一个整数
%e, %f, %g 一个浮点数
%o 一个八进制数
%s 一个字符串
%x 一个十六进制数
%p 一个指针
%n 一个等于读取字符数量的整数
%u 一个无符号整数
%[] 一个字符集
%% 一个精度符号

//一、NSString
/*—————-创建字符串的方法—————-*/

1、创建常量字符串。
NSString *astring = @”This is a String!”;

2、创建空字符串，给予赋值。
NSString *astring = [[NSString alloc] init];
astring = @”This is a String!”;
NSLog(@”astring:%@”,astring);
[astring release];

3、在以上方法中，提升速度:initWithString方法
NSString *astring = [[NSString alloc] initWithString:@”This is a String!”];
NSLog(@”astring:%@”,astring);
[astring release];

4、用标准c创建字符串:initWithCString方法
char *Cstring = “This is a String!”;
NSString *astring = [[NSString alloc] initWithCString:Cstring];
NSLog(@”astring:%@”,astring);
[astring release];

5、创建格式化字符串:占位符（由一个%加一个字符组成）
int i = 1;
int j = 2;
NSString *astring = [[NSString alloc] initWithString:[NSString stringWithFormat:@"%d.This is %i string!",i,j]];
NSLog(@”astring:%@”,astring);
[astring release];

6、创建临时字符串
NSString *astring;
astring = [NSString stringWithCString:"This is a temporary string"];
NSLog(@”astring:%@”,astring);

/*—————-从文件读取字符串:initWithContentsOfFile方法 —————-*/
NSString *path = @”astring.text”;
NSString *astring = [[NSString alloc] initWithContentsOfFile:path];
NSLog(@”astring:%@”,astring);
[astring release];

/*—————-写字符串到文件:writeToFile方法 —————-*/
NSString *astring = [[NSString alloc] initWithString:@”This is a String!”];
NSLog(@”astring:%@”,astring);
NSString *path = @”astring.text”;
[astring writeToFile: path atomically: YES];
[astring release];

/*—————- 比较两个字符串—————-*/
用C比较:strcmp函数
char string1[] = “string!”;
char string2[] = “string!”;
if(strcmp(string1, string2) = = 0)
{
NSLog(@”1″);
}

isEqualToString方法
NSString *astring01 = @”This is a String!”;
NSString *astring02 = @”This is a String!”;
BOOL result = [astring01 isEqualToString:astring02];
NSLog(@”result:%d”,result);

compare方法(comparer返回的三种值)
NSString *astring01 = @”This is a String!”;
NSString *astring02 = @”This is a String!”;
BOOL result = [astring01 compare:astring02] = = NSOrderedSame;
NSLog(@”result:%d”,result);
NSOrderedSame 判断两者内容是否相同

NSString *astring01 = @”This is a String!”;
NSString *astring02 = @”this is a String!”;
BOOL result = [astring01 compare:astring02] = = NSOrderedAscending;
NSLog(@”result:%d”,result);
//NSOrderedAscending 判断两对象值的大小(按字母顺序进行比较，astring02大于astring01为真)

NSString *astring01 = @”this is a String!”;
NSString *astring02 = @”This is a String!”;
BOOL result = [astring01 compare:astring02] = = NSOrderedDescending;
NSLog(@”result:%d”,result);
//NSOrderedDescending 判断两对象值的大小(按字母顺序进行比较，astring02小于astring01为真)

不考虑大 小写比较字符串1
NSString *astring01 = @”this is a String!”;
NSString *astring02 = @”This is a String!”;
BOOL result = [astring01 caseInsensitiveCompare:astring02] = = NSOrderedSame;
NSLog(@”result:%d”,result);
//NSOrderedDescending判断两对象值的大小(按字母顺序进行比较，astring02小于astring01为 真)

不考虑大小写比较字符串2
NSString *astring01 = @”this is a String!”;
NSString *astring02 = @”This is a String!”;
BOOL result = [astring01 compare:astring02
options:NSCaseInsensitiveSearch | NSNumericSearch] = = NSOrderedSame;
NSLog(@”result:%d”,result);

//NSCaseInsensitiveSearch:不区分大小写比较 NSLiteralSearch:进行完全比较，区分大小写 NSNumericSearch:比较字符串的字符个数，而不是字符值。

/*—————-改变字符串的大小写—————-*/
NSString *string1 = @”A String”;
NSString *string2 = @”String”;
NSLog(@”string1:%@”,[string1 uppercaseString]);//大写
NSLog(@”string2:%@”,[string2 lowercaseString]);//小写
NSLog(@”string2:%@”,[string2 capitalizedString]);//首字母大小

/*—————-在串中搜索子串 —————-*/
NSString *string1 = @”This is a string”;
NSString *string2 = @”string”;
NSRange range = [string1 rangeOfString:string2];
int location = range.location;
int leight = range.length;
NSString *astring = [[NSString alloc] initWithString:[NSString stringWithFormat:@"Location:%i,Leight:%i",location,leight]];
NSLog(@”astring:%@”,astring);
[astring release];

/*—————-抽取子串 —————-*/
-substringToIndex: 从字符串的开头一直截取到指定的位置，但不包括该位置的字符
NSString *string1 = @”This is a string”;
NSString *string2 = [string1 substringToIndex:3];
NSLog(@”string2:%@”,string2);

-substringFromIndex: 以指定位置开始（包括指定位置的字符），并包括之后的全部字符
NSString *string1 = @”This is a string”;
NSString *string2 = [string1 substringFromIndex:3];
NSLog(@”string2:%@”,string2);

-substringWithRange: //按照所给出的位置，长度，任意地从字符串中截取子串
NSString *string1 = @”This is a string”;
NSString *string2 = [string1 substringWithRange:NSMakeRange(0, 4)];
NSLog(@”string2:%@”,string2);

const char *fieldValue = [value cStringUsingEncoding:NSUTF8StringEncoding];
const char *fieldValue = [value UTF8String];

NSString 转 NSData
NSString* str= @”kilonet”;
NSData* data=[str dataUsingEncoding:NSUTF8StringEncoding];

Date format用法：
-(NSString *) getDay:(NSDate *) d
{
NSString *s ;
NSDateFormatter *format = [[NSDateFormatter alloc] init];
[format setDateFormat:@"YYYY/MM/dd hh:mm:ss"];
s = [format stringFromDate:d];
[format release];
return s;
}

各地时区获取：

代码
NSDate *nowDate = [NSDate new];
NSDateFormatter *formatter = [[NSDateFormatter alloc] init];
[formatter setDateFormat:@"yyyy/MM/dd HH:mm:ss"];
// 根据时区名字获取当前时间，如果该时区不存在，默认获取系统当前时区的时间
// NSTimeZone* timeZone = [NSTimeZone timeZoneWithName:@"Europe/Andorra"];
// [formatter setTimeZone:timeZone];
//获取所有的时区名字
NSArray *array = [NSTimeZone knownTimeZoneNames];
// NSLog(@”array:%@”,array);
//for循环
// for(int i=0;i<[array count];i++)
// {
// NSTimeZone* timeZone = [NSTimeZone timeZoneWithName:[array objectAtIndex:i]];
// [formatter setTimeZone:timeZone];
// NSString *locationTime = [formatter stringFromDate:nowDate];
// NSLog(@"时区名字:%@ : 时区当前时间: %@",[array objectAtIndex:i],locationTime);
// //NSLog(@"timezone name is:%@",[array objectAtIndex:i]);
// }
//快速枚举法
for(NSString *timeZoneName in array){
[formatter setTimeZone:[NSTimeZone timeZoneWithName:timeZoneName]];
NSLog(@"%@,%@",timeZoneName,[formatter stringFromDate:nowDate]);
}

[formatter release];
[nowDate release];

NSCalendar用法：

-(NSString *) getWeek:(NSDate *) d {
NSCalendar *calendar = [[NSCalendar alloc] initWithCalendarIdentifier:NSGregorianCalendar];
unsigned units = NSYearCalendarUnit | NSMonthCalendarUnit | NSDayCalendarUnit | NSWeekdayCalendarUnit;
NSDateComponents *components = [calendar components:units fromDate:d];
[calendar release];

switch ([components weekday]) {
case 2:
return @"Monday";
break;
case 3:
return @"Tuesday";
break;
case 4:
return @"Wednesday";
break;
case 5:
return @"Thursday";
break;
case 6:
return @"Friday";
break;
case 7:
return @"Saturday";
break;
case 1:
return @"Sunday";
break;
default:
return @"No Week";
break;
}

// 用components，我们可以读取其他更多的数据。

}

4. 用Get方式读取网络数据：

将网络数读取为字符串
- (NSString *) getDataByURL:(NSString *) url {
return [[NSString alloc] initWithData:[NSData dataWithContentsOfURL:[NSURL URLWithString:[url stringByAddingPercentEscapesUsingEncoding:NSUTF8StringEncoding]]] encoding:NSUTF8StringEncoding];
}

//读取网络图片
- (UIImage *) getImageByURL:(NSString *) url {
return [[UIImage alloc] initWithData:[NSData dataWithContentsOfURL:[NSURL URLWithString:[url stringByAddingPercentEscapesUsingEncoding:NSUTF8StringEncoding]]]];
}

多线程
[NSThread detachNewThreadSelector:@selector(scheduleTask) toTarget:self withObject:nil];

-(void) scheduleTask {
//create a pool
NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init];

//release the pool;
[pool release];
}

//如果有参数，则这么使用：
[NSThread detachNewThreadSelector:@selector(scheduleTask:) toTarget:self withObject:[NSDate date]];

-(void) scheduleTask:(NSDate *) mdate {
//create a pool
NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init];

//release the pool;
[pool release];
}

//注意selector里有冒号。
//在线程里运行主线程里的方法

[self performSelectorOnMainThread:@selector(moveToMain) withObject:nil waitUntilDone:FALSE];

6. 定时器NSTimer用法:

代码
// 一个可以自动关闭的Alert窗口

UIAlertView *alert = [[UIAlertView alloc] initWithTitle:nil
message:[@"一个可以自动关闭的Alert窗口"
delegate:nil
cancelButtonTitle:nil //NSLocalizedString(@"OK", @"OK") //取消任何按钮
otherButtonTitles:nil];
//[alert setBounds:CGRectMake(alert.bounds.origin.x, alert.bounds.origin.y, alert.bounds.size.width, alert.bounds.size.height+30.0)];
[alert show];

UIActivityIndicatorView *indicator = [[UIActivityIndicatorView alloc] initWithActivityIndicatorStyle:UIActivityIndicatorViewStyleWhiteLarge];

// Adjust the indicator so it is up a few pixels from the bottom of the alert
indicator.center = CGPointMake(alert.bounds.size.width/2, alert.bounds.size.height-40.0);
[indicator startAnimating];
[alert insertSubview:indicator atIndex:0];
[indicator release];

[NSTimer scheduledTimerWithTimeInterval:3.0f
target:self
selector:@selector(dismissAlert:)
userInfo:[NSDictionary dictionaryWithObjectsAndKeys:alert, @"alert", @"testing ", @"key" ,nil] //如果不用传递参数，那么可以将此项设置为nil.
repeats:NO];

NSLog(@"release alert");
[alert release];

-(void) dismissAlert:(NSTimer *)timer{

NSLog(@"release timer");
NSLog([[timer userInfo] objectForKey:@"key"]);

UIAlertView *alert = [[timer userInfo] objectForKey:@"alert"];
[alert dismissWithClickedButtonIndex:0 animated:YES];

}

定时器停止使用：

[timer invalidate];
timer = nil;

7. 用户缺省值NSUserDefaults读取：

//得到用户缺省值
NSUserDefaults *defs = [NSUserDefaults standardUserDefaults];

//在缺省值中找到AppleLanguages, 返回值是一个数组
NSArray* languages = [defs objectForKey:@"AppleLanguages"];
NSLog(@"all language语言 is %@", languages);

//在得到的数组中的第一个项就是用户的首选语言了
NSLog(@"首选语言 is %@",[languages objectAtIndex:0]);

//get the language & country code
NSLocale *currentLocale = [NSLocale currentLocale];

NSLog(@"Language Code is %@", [currentLocale objectForKey:NSLocaleLanguageCode]);
NSLog(@"Country Code is %@", [currentLocale objectForKey:NSLocaleCountryCode

8. View之间切换的动态效果设置：

SettingsController *settings = [[SettingsController alloc]initWithNibName:@"SettingsView" bundle:nil];
settings.modalTransitionStyle = UIModalTransitionStyleFlipHorizontal; //水平翻转
[self presentModalViewController:settings animated:YES];
[settings release];

9.NSScrollView 滑动用法：

-(void) scrollViewDidScroll:(UIScrollView *)scrollView{
NSLog(@"正在滑动中...");
}

//用户直接滑动NSScrollView，可以看到滑动条
-(void) scrollViewDidEndDecelerating:(UIScrollView *)scrollView {

}

// 通过其他控件触发NSScrollView滑动，看不到滑动条
- (void) scrollViewDidEndScrollingAnimation:(UIScrollView *)scrollView {

}

11.键盘处理系列

//set the UIKeyboard to switch to a different text field when you press return

//switch textField to the name of your textfield
[textField becomeFirstResponder];

srandom(time(NULL)); //随机数种子

id d = random(); // 随机数

4. iPhone的系统目录:

//得到Document目录：
NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
NSString *documentsDirectory = [paths objectAtIndex:0];

//得到temp临时目录：
NSString *tempPath = NSTemporaryDirectory();

//得到目录上的文件地址：
NSString *文件地址 = [目录地址 stringByAppendingPathComponent:@"文件名.扩展名"];

5. 状态栏显示Indicator：

[UIApplication sharedApplication].networkActivityIndicatorVisible = YES;

6.app Icon显示数字：

- (void)applicationDidEnterBackground:(UIApplication *)application{
[[UIApplication sharedApplication] setApplicationIconBadgeNumber:5];
}

7.sqlite保存地址：

代码
NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
NSString *thePath = [paths objectAtIndex:0];
NSString *filePath = [thePath stringByAppendingPathComponent:@"kilonet1.sqlite"];

NSString *dbPath = [[[NSBundle mainBundle] resourcePath]
stringByAppendingPathComponent:@"kilonet2.sqlite"];

8.Application退出：exit(0);

9. AlertView，ActionSheet的cancelButton点击事件：

代码
-(void) actionSheet UIActionSheet *) actionSheet didDismissWithButtonIndex:(NSInteger) buttonIndex {
NSLog(@"cancel actionSheet........");
//当用户按下cancel按钮
if( buttonIndex == [actionSheet cancelButtonIndex]) {
exit(0);
}
// //当用户按下destructive按钮
// if( buttonIndex == [actionSheet destructiveButtonIndex]) {
// // DoSomething here.
// }
}

- (void)alertView:(UIAlertView *)alertView willDismissWithButtonIndex:(NSInteger)buttonIndex {
NSLog(@"cancel alertView........");
if (buttonIndex == [alertView cancelButtonIndex]) {
exit(0);
}
}

10.给Window设置全局的背景图片：
window.backgroundColor = [UIColor colorWithPatternImage:[UIImage imageNamed:@"coolblack.png"]];

11. UITextField文本框显示及对键盘的控制:

代码
#pragma mark -
#pragma mark UITextFieldDelegate
//控制键盘跳转
- (BOOL)textFieldShouldReturn:(UITextField *)textField {

if (textField == _txtAccount) {
if ([_txtAccount.text length]==0) {
return NO;
}
[_txtPassword becomeFirstResponder];
} else if (textField == _txtPassword) {
[_txtPassword resignFirstResponder];
}

return YES;
}

//输入框背景更换
-(BOOL) textFieldShouldBeginEditing:(UITextField *)textField{

[textField setBackground:[UIImage imageNamed:@"ctext_field_02.png"]];

return YES;
}

-(void) textFieldDidEndEditing:(UITextField *)textField{
[textField setBackground:[UIImage imageNamed:@"ctext_field_01.png"]];
}

12.UITextField文本框前面空白宽度设置以及后面组合按钮设置：

代码
//给文本输入框后面加入空白
_txtAccount.rightView = _btnDropDown;
_txtAccount.rightViewMode = UITextFieldViewModeAlways;

//给文本输入框前面加入空白
CGRect frame = [_txtAccount frame];
frame.size.width = 5;
UIView *leftview = [[UIView alloc] initWithFrame:frame];
_txtAccount.leftViewMode = UITextFieldViewModeAlways;
_txtAccount.leftView = leftview;

13. UIScrollView 设置滑动不超出本身范围：

[fcScrollView setBounces:NO];

14. 遍历View里面所有的Subview：

代码
NSLog(@"subviews count=%d",[self.view.subviews count]);
if ([self.view.subviews count] > 0) {
for (UIView *curView in self.view.subviews) {
NSLog(@”view.subviews=%@”, [NSString stringWithUTF8String:object_getClassName(curView)]);
}
}

14. 在drawRect里画文字：

UIFont * f = [UIFont systemFontOfSize:20];

[[UIColor darkGrayColor] set];

NSString * text = @”hi \nKiloNet”;

[text drawAtPoint:CGPointMake(center.x,center.y) withFont:f];

15. NSArray查找是否存在对象时用indexOfObject,如果不存在则返回为NSNotFound.

16. NString与NSArray之间相互转换：

array = [string componentsSeparatedByString:@","];
string = [[array valueForKey:@"description"] componentsJoinedByString:@”,”];

17. TabController随意切换tab bar：

[self.tabBarController setSelectedIndex:tabIndex];

或者 self.tabBarController.selectedIndex = tabIndex;

或者实现下面的delegate来扑捉tab bar的事件：

代码-(BOOL) tabBarController:(UITabBarController *)tabBarController shouldSelectViewController:(UIViewController *)viewController { if ([viewController.tabBarItem.title isEqualToString: NSLocalizedString(@"Logout",nil)]) { [self showLogout]; return NO; } return YES;}

18. 自定义View之间切换动画：
代码
- (void) pushController: (UIViewController*) controller
withTransition: (UIViewAnimationTransition) transition
{
[UIView beginAnimations:nil context:NULL];
[self pushViewController:controller animated:NO];
[UIView setAnimationDuration:.5];
[UIView setAnimationBeginsFromCurrentState:YES];
[UIView setAnimationTransition:transition forView:self.view cache:YES];
[UIView commitAnimations];
}

CATransition *transition = [CATransition animation];
transition.duration = kAnimationDuration;
transition.timingFunction = [CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionEaseInEaseOut];
transition.type = kCATransitionPush;
transition.subtype = kCATransitionFromTop;
transitioning = YES;
transition.delegate = self;
[self.navigationController.view.layer addAnimation:transition forKey:nil];

self.navigationController.navigationBarHidden = NO;
[self.navigationController pushViewController:tableViewController animated:YES];

20.计算字符串长度：

CGFloat w = [title sizeWithFont:[UIFont fontWithName:@"Arial" size:18]].width;

23.在使用UISearchBar时，将背景色设定为clearColor，或者将translucent设为YES，都不能使背景透明，经过一番研究，发现了一种超级简单和实用的方法：

1
[[searchbar.subviews objectAtIndex:0]removeFromSuperview];

背景完全消除了，只剩下搜索框本身了。

24. 图像与缓存 :

UIImageView *wallpaper = [[UIImageView alloc] initWithImage:

[UIImage imageNamed:@"icon.png"]]; // 会缓存图片

UIImageView *wallpaper = [[UIImageView alloc] initWithImage:

[UIImage imageWithContentsOfFile:@"icon.png"]]; // 不会缓存图片

25. iphone-常用的对视图图层(layer)的操作

对图层的操作：

(1.给图层添加背景图片：
myView.layer.contents = (id)[UIImage imageNamed:@"view_BG.png"].CGImage;

(2.将图层的边框设置为圆脚
myWebView.layer.cornerRadius = 8;
myWebView.layer.masksToBounds = YES;

(3.给图层添加一个有色边框
myWebView.layer.borderWidth = 5;
myWebView.layer.borderColor = [[UIColor colorWithRed:0.52 green:0.09 blue:0.07 alpha:1] CGColor];