1.取字符串中的某段字符串 
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NSString *str =@"12sadfsdf56afsdf";   
NSLog(@"%@",str); 
NSString *thrStr = [strstringByReplacingOccurrencesOfString:@"56"withString:@"88"];
NSLog(@"%@",thrStr); 
即把12sadfsdf56afsdf中的56替换为88，替换后字符串为：12sadfsdf88afsdf

2.简单plist获取
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NSString *path = [[NSBundlemainBundle]pathForResource:@"Array"ofType:@"plist"];  
NSMutableDictionary *data = [[NSMutableDictionaryalloc]initWithContentsOfFile:path];  
NSLog(@"%d",[datacount]);  
NSLog(@"%@",[dataallValues]);  
NSLog(@"------------") ;   
NSArray *ary = [dataallKeys]; 
NSLog(@"%d",[arycount]); 
NSArray *array = [NSArrayarrayWithArray:ary];   
for(int i=0;i<[arraycount];i++)   
{   
    NSLog(@"\n value = %@",[arrayobjectAtIndex:i]);    
}   
NSArray *getArray = [[dataallValues]objectAtIndex:5];

NSLog(@"get_array:%@",getArray);  
 
3.状态栏和UINavigationBar设置成透明 
[[UIApplicationsharedApplication]setStatusBarStyle:UIStatusBarStyleBlackTranslucent];  //状态栏设置为透明 
theNavigationController.navigationBar.barStyle =UIBarStyleBlackTranslucent;   //设置navigationBar为透明

  
4.设置object圆角，如UIView、UIImageView等 
简单几步： 
一.导入QuartzCore.framework框架   #import    
二.object.layer.masksToBounds=YES; 
三.object.layer.cornerRadius=XXX; 
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UIImageView *testImageView = [[UIImageViewalloc]initWithImage:[UIImageimageNamed:@"1.jpg"]];  
[testImageViewsetFrame:CGRectMake(20,20,100,100)];  
testImageView.layer.masksToBounds =YES;   
testImageView.layer.cornerRadius =50/2;   //设置的角度，改变查看效果   
testImageView.layer.borderWidth =5;   //边框宽度   
testImageView.layer.borderColor = [UIColoryellowColor].CGColor;   //边框颜色  
[self.viewaddSubview:testImageView];  
[testImageViewrelease];  

5.程序是启动状态时设置屏幕一直亮 
    UIApplication *appDelegate = [UIApplicationsharedApplication];
    appDelegate.idleTimerDisabled =YES;

6.设置UITableViewCell显示子标题 
初始化时：cell = [[UITableViewCellalloc]initWithStyle:UITableViewCellStyleSubtitlereuseIdentifier:CellIdentifier]; 
此处样式应注意，即设置为显示子标题样式，默认样式为不显示子标题，设置完后可用： 
cell.detailTextLabel.text =@"详细标签";    设置子标题

7.给UIView设置阴影效果 
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UIView *showView = [[UIViewalloc]initWithFrame:CGRectMake(10,150,100,100)];   
showView.backgroundColor = [UIColorredColor];  
showView.layer.shadowOffset =CGSizeMake(15,5);   
showView.layer.shadowOpacity =0.6;   
showView.layer.shadowColor = [UIColorblackColor].CGColor;  
[self.viewaddSubview:showView];   
[showViewrelease];  

8.设置UITableView选中行数的位置 
[self.tableViewselectRowAtIndexPath:[NSIndexPathindexPathForRow:5inSection:0]animated:NOscrollPosition:UITableViewScrollPositionMiddle];  
//selectRowAtIndexPath设置行数和section   scrollPosition设置滚动到的位置（4项可供选择）

9.UITextField每次操作调用的代理，可根据需求作相应改变 
- (BOOL) textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string 
{ 
    NSMutableString *newString = [[textField.textmutableCopy]autorelease]; 
    [newStringreplaceCharactersInRange:rangewithString:string];   //得到改变的字符串
}

10.如何用UIColor生成UIImage

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- (void)viewDidLoad   
{
    [superviewDidLoad];  
    UIImageView *imageView = [[UIImageView alloc] initWithFrame:CGRectMake(10,10,100,100)];  
    UIImage *image = [self createImageWithColor:[UIColoryellowColor]];   //生成一张黄颜色的图片    
    [imageViewsetImage:image];   
    [self.viewaddSubview:imageView]; 
    [imageViewrelease];  
}    
- (UIImage *) createImageWithColor: (UIColor *) color 
{   
    CGRect rect = CGRectMake(0.0f,0.0f,1.0f,1.0f);  
   UIGraphicsBeginImageContext(rect.size);   
   CGContextRef context =UIGraphicsGetCurrentContext();  
   CGContextSetFillColorWithColor(context, [colorCGColor]);  
    CGContextFillRect(context, rect);   
   UIImage *theImage =UIGraphicsGetImageFromCurrentImageContext();  
   UIGraphicsEndImageContext();   
    return theImage;   
}