一些常见又好用的代码

部分一：关于改变label

Returns a rectangle that is smaller or larger than the source rectangle, with the same center point.

CGContextRef context=UIGraphicsGetCurrentContext();

//draws a rectangle

CGContextStrokeRect(context, CGRectInset(self.bounds,
1.0,
1.0));

[super
drawTextInRect: CGRectInset(rect,
5, 5)];
／／通过以上得代码，画个框，在一个更内部得范围内画了字符。。。。
部分二

#import
<Foundation/Foundation.h>

@interface NSString (StringCategories)
-(NSString*) basePictureName;
@end

产生一个类，然后把类名搞在括号里，interface 名称改为要extend 的 类

#import
"StringCategories.h"

@implementation NSString (StringCategories)
-(NSString*) basePictureName{

return [self
stringByAppendingString:@"IO"];
}
@end
／／通过以上的方式，也可以分开同一个类在不同的文件中实现

部分3
协议，我们最常用的就是在interface中<protocolName>, 也可以自定义protocol.
@protocol ProtocolName <Class>
-(void) methodName1...
@optional
....
@end

还有一个用法就是作为范型的一个检查:
@property (non atomic,assign) id<protocol> propertyName
从这个定义来看，这个属性没有特定的类型要求，来自id，但要求是符合protocol。。。 。。

部分四 optional method
我们看到optional method,一般用在两个地方： class category 和custom protocol，但需要一个机制来检查特定对象有没有实现optional的方法：
myclass * mc=[[myclass alloc] init];
if ([mc respondstoSelector:@selector(woohoo)])// 这样就返回了是否支持的结果
如果支持就调用[mc woohoo]
//

-(BOOL) respondsToSelector:(SEL)aSelector
{

NSLog(@"%@",NSStringFromSelector(aSelector));

return [super
respondsToSelector:aSelector];
}
在application delegate中，其实很多方式多进行了判断，以下就是一些顺序。

applicationWillResignActive:
2012-04-08 11:16:42.872 TestUIEffect[707:f803] applicationDidEnterBackground:
2012-04-08 11:16:42.919 TestUIEffect[707:f803] applicationWillEnterForeground:
2012-04-08 11:16:42.919 TestUIEffect[707:f803] applicationWillSuspend:
2012-04-08 11:16:42.920 TestUIEffect[707:f803] application:didResumeWithOptions:
2012-04-08 11:16:42.962 TestUIEffect[707:f803] application:didFinishLaunchingWithOptions:

部分五 ：
NSRange/NSNOtfound／NSregularexpression/NSTextCheckingResult/NSMutalbeString/

//NSMakeRange(<#NSUInteger loc#>, <#NSUInteger len#>)
//NSRangeFromString(<#NSString *aString#>)

部分六：
[NSumber numberWithInt:5] //初始化


[NSUserDefaults standardUserDefaults] 标准应用本地用户存储

[[NSUserDefaults standardUserDefaults] registerDefaults:data] 存入数据

NSDictionary* data=[NSDictionary
dictionaryWithObjectsAndKeys:[NSNumber
numberWithInt:4],@"cardRows",[NSNumber
numberWithInt:3],@"cardColums",
nil];
[[NSUserDefaults
standardUserDefaults] registerDefaults:data];

备注：由于nsinteger 本身不是数字，不能直接算术运算，可以通过 intValue来获取,

NSUserDefaults* ud=[NSUserDefaults
standardUserDefaults];

int therows=[ud integerForKey:@"cardRows"];

int thecolumns=[[ud objectForKey:@"cardColumns"]
intValue];

部分七：
NSData 是用于bytes序列的，一般会在网络访问中用到，还有就是序列化需要的时候，比如把 UIColor转化为 NSData存储到 NSUserDefaults

Archives and serializations are two ways in which you can create architecture-independent byte streams of hierarchical data. Byte streams can then be written to a file or transmitted to another process, perhaps over a network. When the byte stream is decoded,
the hierarchy is regenerated. Archives provide a detailed record of a collection of interrelated objects and values. Serializations record only the simple hierarchy of property-list values.

NSDictionary* colorDict=[NSDictionary
dictionaryWithObjectsAndKeys:[NSKeyedArchiver
archivedDataWithRootObject:[UIColor
blueColor]],@"mycolor",nil];
[[NSUserDefaults
standardUserDefaults] registerDefaults:colorDict];

You should read this document to learn how to create and extract archived representations of object graphs.

NSDictionary* colorDict=[NSDictionary
dictionaryWithObjectsAndKeys:[NSKeyedArchiver
archivedDataWithRootObject:[UIColor
blueColor]],@"mycolor",nil];
[[NSUserDefaults
standardUserDefaults] registerDefaults:colorDict];

NSString *str = @"abc"; NSString *astr = @"efg"; NSArray *Array = [NSArray arrayWithObjects:str, astr, nil]; //保存数据 NSString *Path = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) objectAtIndex:0]; NSString *filename = [Path stringByAppendingPathComponent:@"test.plist"]; [NSKeyedArchiver archiveRootObject:Array toFile:filename]; str = @"a"; astr = @""; //加载数据 NSArray *arr = [NSKeyedUnarchiver unarchiveObjectWithFile: filename]; str = [arr objectAtIndex:0]; astr = [arr objectAtIndex:1]; NSLog(@"str:%@",str); NSLog(@"astr:%@",astr);