iOS字符串操作总结
//将NSData转化为NSString
NSString* str = [[NSString alloc] initWithData:response encoding:NSUTF8StringEncoding];
//将NSString 转化为NSData (NSString.h)
- (NSData *)dataUsingEncoding:(NSStringEncoding)encoding;
//在一个字符串中删除一个字符或字符串
[_display deleteCharactersInRange:NSMakeRange(index_of_char_to_remove, 1)];
整数型转换为字符串
NSString *returnStr;
returnStr = [[NSNumber numberWithInt:row] stringValue];
NSString *******************************************************************************************/
//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!";
[astring release]; NSLog(@"astring:%@",astring);
//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);
//扩展路径
NSString *Path = @"~/NSData.txt";
NSString *absolutePath = [Path stringByExpandingTildeInPath]; NSLog(@"absolutePath:%@",absolutePath);
NSLog(@"Path:%@",[absolutePath stringByAbbreviatingWithTildeInPath]);
//文件扩展名
NSString *Path = @"~/NSData.txt";
NSLog(@"Extension:%@",[Path pathExtension]);
/******************************************************************************************* NSMutableString *******************************************************************************************/
/*---------------给字符串分配容量----------------*/
//stringWithCapacity:
NSMutableString *String;
String = [NSMutableString stringWithCapacity:40];
/*---------------在已有字符串后面添加字符----------------*/ //appendString: and appendFormat:
NSMutableString *String1 = [[NSMutableString alloc] initWithString:@"This is a NSMutableString"];
//[String1 appendString:@", I will be adding some character"];
[String1 appendFormat:[NSString stringWithFormat:@", I will be adding some character"]];
NSLog(@"String1:%@",String1); */
/*--------在已有字符串中按照所给出范围和长度删除字符------*/ //deleteCharactersInRange:
NSMutableString *String1 = [[NSMutableString alloc] initWithString:@"This is a NSMutableString"];
[String1 deleteCharactersInRange:NSMakeRange(0, 5)]; NSLog(@"String1:%@",String1);
/*--------在已有字符串后面在所指定的位置中插入给出的字符串------*/
//-insertString: atIndex:
NSMutableString *String1 = [[NSMutableString alloc] initWithString:@"This is a NSMutableString"];
[String1 insertString:@"Hi! " atIndex:0];
NSLog(@"String1:%@",String1);
/*--------将已有的空符串换成其它的字符串------*/
//-setString:
NSMutableString *String1 = [[NSMutableString alloc] initWithString:@"This is a NSMutableString"];
[String1 setString:@"Hello Word!"];
NSLog(@"String1:%@",String1);
/*--------按照所给出的范围，和字符串替换的原有的字符------*/
//-setString:
NSMutableString *String1 = [[NSMutableString alloc] initWithString:@"This is a NSMutableString"];
[String1 replaceCharactersInRange:NSMakeRange(0, 4) withString:@"That"]; NSLog(@"String1:%@",String1);
/*-------------判断字符串内是否还包含别的字符串(前缀，后缀)-------------*/ //01：检查字符串是否以另一个字符串开头
- (BOOL) hasPrefix: (NSString *) aString;
NSString *String1 = @"NSStringInformation.txt";
[String1 hasPrefix:@"NSString"] = = 1 ? NSLog(@"YES") : NSLog(@"NO");
[String1 hasSuffix:@".txt"] = = 1 ? NSLog(@"YES") : NSLog(@"NO");
//02：查找字符串某处是否包含其它字符串
- (NSRange) rangeOfString: (NSString *) aString，这一点前面在串中搜索子串用到过; /******************************************************************************************* NSArray *******************************************************************************************/
/*---------------------------创建数组------------------------------*/ //NSArray *array = [[NSArray alloc] initWithObjects: @"One",@"Two",@"Three",@"Four",nil];
self.dataArray = array;
[array release];
//- (unsigned) Count;数组所包含对象个数；
NSLog(@"self.dataArray cound:%d",[self.dataArray count]);
//- (id) objectAtIndex: (unsigned int) index;获取指定索引处的对象; NSLog(@"self.dataArray cound 2:%@",[self.dataArray objectAtIndex:2]);
/*--------------------------从一个数组拷贝数据到另一数组(可变数级)----------------------------*/
//arrayWithArray:
//NSArray *array1 = [[NSArray alloc] init];
NSMutableArray *MutableArray = [[NSMutableArray alloc] init];
NSArray *array = [NSArray arrayWithObjects: @"a",@"b",@"c",nil]; NSLog(@"array:%@",array);
MutableArray = [NSMutableArray arrayWithArray:array]; NSLog(@"MutableArray:%@",MutableArray);
array1 = [NSArray arrayWithArray:array];
NSLog(@"array1:%@",array1);
//Copy //id obj;
NSMutableArray *newArray = [[NSMutableArray alloc] init];
NSArray *oldArray = [NSArray arrayWithObjects: @"a",@"b",@"c",@"d",@"e",@"f",@"g",@"h",nil];
NSLog(@"oldArray:%@",oldArray);
for(int i = 0; i < [oldArray count]; i++) { obj = [[oldArray objectAtIndex:i] copy]; [newArray addObject: obj]; }
//NSLog(@"newArray:%@", newArray);
[newArray release];
//快速枚举
//NSMutableArray *newArray = [[NSMutableArray alloc] init];
NSArray *oldArray = [NSArray arrayWithObjects: @"a",@"b",@"c",@"d",@"e",@"f",@"g",@"h",nil];
NSLog(@"oldArray:%@",oldArray);
for(id obj in oldArray) { [newArray addObject: obj]; }
// NSLog(@"newArray:%@", newArray);
[newArray release];
//Deep copy
//NSMutableArray *newArray = [[NSMutableArray alloc] init];
NSArray *oldArray = [NSArray arrayWithObjects: @"a",@"b",@"c",@"d",@"e",@"f",@"g",@"h",nil];
NSLog(@"oldArray:%@",oldArray);
newArray = (NSMutableArray*)CFPropertyListCreateDeepCopy(kCFAllocatorDefault, (CFPropertyListRef)oldArray, kCFPropertyListMutableContainers); NSLog(@"newArray:%@", newArray);
[newArray release];
//Copy and sort
//NSMutableArray *newArray = [[NSMutableArray alloc] init];
NSArray *oldArray = [NSArray arrayWithObjects: @"b",@"a",@"e",@"d",@"c",@"f",@"h",@"g",nil];
NSLog(@"oldArray:%@",oldArray);
NSEnumerator *enumerator;
enumerator = [oldArray objectEnumerator];
id obj;
while(obj = [enumerator nextObject]) { [newArray addObject: obj]; }
[newArray sortUsingSelector:@selector(compare:)];
NSLog(@"newArray:%@", newArray);
[newArray release];
/*---------------------------切分数组------------------------------*/ //从字符串分割到数组－ componentsSeparatedByString:
NSString *string = [[NSString alloc] initWithString:@"One,Two,Three,Four"]; NSLog(@"string:%@",string);
NSArray *array = [string componentsSeparatedByString:@","]; NSLog(@"array:%@",array);
[string release];
//从数组合并元素到字符串- componentsJoinedByString:
NSArray *array = [[NSArray alloc] initWithObjects:@"One",@"Two",@"Three",@"Four",nil];
NSString *string = [array componentsJoinedByString:@","]; NSLog(@"string:%@",string); /******************************************************************************************* NSMutableArray *******************************************************************************************/
/*---------------给数组分配容量----------------*/
//NSArray *array;
array = [NSMutableArray arrayWithCapacity:20];
/*--------------在数组末尾添加对象----------------*/
//- (void) addObject: (id) anObject;
//NSMutableArray *array = [NSMutableArray arrayWithObjects: @"One",@"Two",@"Three",nil];
[array addObject:@"Four"];
NSLog(@"array:%@",array);
/*--------------删除数组中指定索引处对象----------------*/
//-(void) removeObjectAtIndex: (unsigned) index;
//NSMutableArray *array = [NSMutableArray arrayWithObjects: @"One",@"Two",@"Three",nil];
[array removeObjectAtIndex:1];
NSLog(@"array:%@",array);
/*-------------数组枚举---------------*/
//- (NSEnumerator *)objectEnumerator;从前向后
//NSMutableArray *array = [NSMutableArray arrayWithObjects: @"One",@"Two",@"Three",nil];
NSEnumerator *enumerator;
enumerator = [array objectEnumerator];
id thingie;
while (thingie = [enumerator nextObject]) { NSLog(@"thingie:%@",thingie); } //- (NSEnumerator *)reverseObjectEnumerator;从后向前
//NSMutableArray *array = [NSMutableArray arrayWithObjects: @"One",@"Two",@"Three",nil];
NSEnumerator *enumerator;
enumerator = [array reverseObjectEnumerator];
id object;
while (object = [enumerator nextObject]) { NSLog(@"object:%@",object); } //快速枚举
//NSMutableArray *array = [NSMutableArray arrayWithObjects: @"One",@"Two",@"Three",nil];
for(NSString *string in array) { NSLog(@"string:%@",string); } /******************************************************************************************* NSDictionary *******************************************************************************************/
/*------------------------------------创建字典------------------------------------*/
//- (id) initWithObjectsAndKeys;
//NSDictionary *dictionary = [[NSDictionary alloc] initWithObjectsAndKeys:@"One",@"1",@"Two",@"2",@"Three",@"3",nil];
NSString *string = [dictionary objectForKey:@"One"];
NSLog(@"string:%@",string);
NSLog(@"dictionary:%@",dictionary);
[dictionary release]; /******************************************************************************************* NSMutableDictionary *******************************************************************************************/
/*------------------------------------创建可变字典------------------------------------*/
//创建 NSMutableDictionary *dictionary = [NSMutableDictionary dictionary]; //添加字典 [dictionary setObject:@"One" forKey:@"1"];
[dictionary setObject:@"Two" forKey:@"2"];
[dictionary setObject:@"Three" forKey:@"3"];
[dictionary setObject:@"Four" forKey:@"4"];
NSLog(@"dictionary:%@",dictionary);
//删除指定的字典 [dictionary removeObjectForKey:@"3"]; NSLog(@"dictionary:%@",dictionary); /******************************************************************************************* NSValue（对任何对象进行包装） *******************************************************************************************/
/*--------------------------------将NSRect放入NSArray中------------------------------------*/
//将NSRect放入NSArray中
NSMutableArray *array = [[NSMutableArray alloc] init];
NSValue *value;
CGRect rect = CGRectMake(0, 0, 320, 480);
value = [NSValue valueWithBytes:&rect objCType:@encode(CGRect)];
[array addObject:value];
NSLog(@"array:%@",array);
//从Array中提取
value = [array objectAtIndex:0];
[value getValue:&rect];
NSLog(@"value:%@",value); /******************************************************************************************* 从目录搜索扩展名为jpg的文件 *******************************************************************************************/
//NSFileManager *fileManager = [NSFileManager defaultManager];
NSString *home;
home = @"../Users/";
NSDirectoryEnumerator *direnum;
direnum = [fileManager enumeratorAtPath: home];
NSMutableArray *files = [[NSMutableArray alloc] init];
//枚举 NSString *filename;
while (filename = [direnum nextObject]) { if([[filename pathExtension] hasSuffix:@"jpg"]){ [files addObject:filename]; } }
//快速枚举 //for(NSString *filename in direnum) { if([[filename pathExtension] isEqualToString:@"jpg"])
{ [files addObject:filename]; } }
NSLog(@"files:%@",files);
//枚举 NSEnumerator *filenum;
filenum = [files objectEnumerator];
while (filename = [filenum nextObject]) {NSLog(@"filename:%@",filename);}
//快速枚举 //for(id object in files) { NSLog(@"object:%@",object);}
#importint main (int argc, const char * argv[]) {
NSAutoreleasePool * pool = [[NSAutoreleasePool alloc] init];
//创建字符串
NSString *height;
/**类方法：
+(id) stringWithFormat: (NSString *) format,...
通过格式字符串和参数来创建NSString
省略号（。。。）：可以接受多个以逗号分割的参数。
这声明方法时添加加号（＋），那么这个方法为类方法，不需要创建实例就可以调用，通常用于创建心的实例，我们称用来创建新对象的类方法为工厂方法。
－－－－－－－－－－－－－－－－－－－
objective－c运行时生成一个类的时候，它会创建一个代表该类的类对象。类对象包含了指向超类的指针，类名，和指向类方法列表的指针。类对象还包含一个long型数据，为新创建的类实例对象指定大小（以字节为单位）
类方法可以用来访问全局数据。
实例方法要用前导减号（－）来开始声明
*/
height=[NSString stringWithFormat:@"you heigh is %d feet,%d inches",5,11];
NSLog(height);
//length 返回字符串中字符的个数。－（unsigned int) length;
if([height length]>5){
NSLog(@"height length ------");
}
//字符串比较
/**
isEqualToString :可以用来比较接收方和当作参数传递来的字符串的内容是否相同，返回yes和no
*/
NSString *thing1=@"hello";
NSString *thing2=[[NSString alloc] initWithString:@"hello"];
if([thing1 isEqualToString:thing2]){
NSLog(@"they are same");
}
/**
==:只判断指针数值，而不是它们所指向的内容
*/
if(thing1==thing2){
NSLog(@"== same");
}
/*
compare:比较两个字符串。区分大小写
compare将接收对象和传递来的字符串逐个字符的进行比较，它返回一个NSComparisonResult(枚举类型)来显示结果。
typedef enum _NSComparisonResult{
NSOrderedAscending=-1;
NSOrderedsame;
NSOrderedDescending;
} NSComparisonResult;
*/
[thing1 compare:thing2];
if(NSOrderedSame==[thing1 compare:thing2]){
NSLog(@"compare same");
}
//compare：options:
/***
-(NSComparisonResult) compare:(NSString *) string
options:(unsinged) mask;
options 是一个位掩码，可以使用|添加选项标记
选项：
NSCaseInsensitiveSearch:不区分大小写字符
NSLiteralSearch:进行完全比较，区分大小写
NSNumbericSearch:比较字符串的字符个数，而不是字符值
*/
if([thing1 compare:thing2 options:NSCaseInsensitiveSearch|
NSNumericSearch]==NSOrderedSame){
NSLog(@"they match");
}
/**
以某个字符串开始或结尾
-(BOOL) hasPrefix:(NSString *) aString;
-(BOOL) hasSuffix:(NSString *) aString;
*/
NSString *fileName=@"aabbbcc";
if([fileName hasPrefix:@"aa"]){
NSLog(@"begin with aa");
}
if([fileName hasSuffix:@"cc"]){
NSLog(@"end with cc");
}
//NSMutableString 可变字符串
//SString 是不可变的，一旦NSString 被创建了，我们就不能改变它。
//+(id) stringWithCapacity:(unsinged) capacity; capacity:是给NSMutableString的一个建议，字符串的大小并不局限于所提供的大小，这个容量仅是个最优值。
NSMutableString *str=[NSMutableString stringWithCapacity:40];
[str appendFormat:@"sdfsdf%d",5];
[str appendString:@"ssssssss"];
NSLog(str);
//删除字符串
//-(void) deleteCharactersInRange:(NSRange) range;
NSMutableString *ms;
ms=[NSMutableString stringWithCapacity:50];
[ms appendString:@"aabbccdd"];
NSRange range;
range=[ms rangeOfString:@"cc"];
[ms deleteCharactersInRange:range];
NSLog(ms);
//截取字符串
[string substringWithRange:NSMakeRange(0, 10)];
//与实例方法一样，继承对类方法也同样适用
//------------------集合－－－－－－－－－－－－－－
//NSArray ,NSDictionary
/**
NSArray 是一个cocoa类，用来存储对象的有序列表。
NSArray有两个限制：1，它只能存储objective－c的对象，而不能存储c语言中的基本数据类型如int，float，enum，struct，或者nsarray中的随机指针。2，不能这nsarray中存储nil
类方法：
arrayWithObjects:创建一个新的nsarray。发送一个以逗号分割的对象列表，这列表结尾添加nil代表列表结束，（这就是不能这nsarray中存储nil的原因）
*/
NSArray *array=[NSArray arrayWithObjects:@"aa",@"bb",@"cc",nil];
//-(unsigned) count; 取得包含对象的个数
//-(id) objectAtIndex:(unsigned int) index; 取得索引位置的对象
int i;
for (i=0; i<[array count]; i++) {
NSLog(@"index %d has %@",i,[array objectAtIndex:i]);
}
//------------切分数组
//-componentsSeparatedByString:
NSString *ns=@"sdf,dsfs,dfd,fdf,df,dd";
NSArray *comArr=[ns componentsSeparatedByString:@","];
for(int i=0;i<[comArr count];i++){
NSLog(@"componentsSeparatedByString===%@",[comArr objectAtIndex:i]);
}
//componentJoinedByString: 合并nsarray中的元素来创建字符串
NSString *joinedStr=[comArr componentsJoinedByString:@"-->"];
NSLog(@"joined---= %@",joinedStr);
//可变数组
NSMutableArray *mutableArr=[NSMutableArray arrayWithCapacity:40];
[mutableArr addObject:@"aa"];
[mutableArr addObject:@"bb"];
[mutableArr addObject:@"cc"];
[mutableArr addObject:@"dd"];
for(int i=0;i<[mutableArr count];i++){
NSLog(@"mutableArr==%@",[mutableArr objectAtIndex:i]);
}
//----- -(void) removeObjectAtIndex:(unsinged) index; 删除指定索引的对象,
//删除一个对象之后，数组中并没有留下漏洞，被删除对象后面的数组元素的哦被前移来填补空缺
[mutableArr removeObjectAtIndex:2];
for(int i=0;i<[mutableArr count];i++){
NSLog(@"removeObjectAtIndex == %@",[mutableArr objectAtIndex:i]);
}
//枚举
//NSEnumerator ,它是cocoa用来描述这种集合迭代运输的方法
//-(NSEnumerator *) objectEnumerator;
NSEnumerator *enumerator=[mutableArr objectEnumerator];
id thingie;
while(thingie=[enumerator nextObject]){
NSLog(@"i found %@",thingie);
}
//快速枚举
for(NSString *string in mutableArr){
NSLog(@"for in == %@",string);
}
//NSDictionary 字典
/*
NSDictionary 是在给定的关键字（通常是一个NSString字符串）下存储一个数值（可以是任何类型的对象）。然后你可以用这个关键字来查找相应的数值。
NSDictionary 是键查询的优化存储方式。它可以立即找出要查询的数据，而不需要遍历整个数组进行查找。
＋（id) dictionaryWithObjectAndKeys:(id) firstObject,....;
该方法接收对象和关键字交替出现的系列，以nil值作为终止符号。
**/
NSDictionary *dic=[NSDictionary dictionaryWithObjectsAndKeys:@"aaa",@"a",@"bbb",@"b",nil];
NSString *dicStr=[dic objectForKey:@"a"];
if([dicStr isEqualToString:@"aaa"]){
NSLog(@"------------00000000000000000");
}
//可变字典
NSMutableDictionary *mutableDic=[NSMutableDictionary dictionaryWithCapacity:50];
[mutableDic setObject:@"1111" forKey:@"1"];
[mutableDic setObject:@"222" forKey:@"2"];
//删除 -(void) removeObjectForKe:(id) key;
[mutableDic removeObjectForKey:@"2"];
NSArray *keyArr=[mutableDic allKeys];
for(NSString *str in keyArr){
NSLog(@"key== %@",str);
NSLog(@"value== %@",[mutableDic objectForKey:str]);
}
//各种数值，NSNumber NSValue
/*
cocoa 提供了NSNumber类来包装基本数据类型
+(NSNumber *) numberWithChar:(char) value;
+(NSNumber *) numberWithInt:(int) value;
+(NSNumber *) numberWithFloat:(float) value;
+(NSNumber *) numberWthiBool:(BOOL) value;
-(char) charValue;
-(int) intVlaue;
-(float) floatValue;
-(BOOL) boolValue;
-(NSString *) stringValue;
**/
NSNumber *number;
number=[NSNumber numberWithInt:3];
[mutableDic setObject:number forKey:@"int"];
int num=[[mutableDic objectForKey:@"int"] intValue];
NSLog(@"int object value== %d",num);
//NSValue .NSNumber实际上是NSValue的子类，NSValue可以包装任意值
/**
+(NSValue *) valueWithBytes:(const void *) value objCType:(const char *) type;
传递的参数是你想要包装的数值的地址，通常，得到的是你想要存储的变量的地址（在c语言里适用操作符 & ），你也可以提供一个描述这个数据类型的字符串，通常用来说明struct中实体的类型和大小。你不用自己写代码
来生成这个字符串，@encode编译器指令可以接受数据类型的名称并为你生成合适的字符串
*/
NSRect rect= NSMakeRect(1, 2, 30, 40);
NSValue *value;
value=[NSValue valueWithBytes:&rect objCType:@encode(NSRect)];
NSMutableArray *mr=[NSMutableArray arrayWithCapacity:50];
[mr addObject:value];
//getValue 提取数据
/**
-(void) getValue:(void *) value; 要传递的是存储这个数值的变量的地址
*/
/***
value=[mr objectAtIndex:0];
NSRect r;
NSLog(@"00000 ===%@",r);
[value getValue:&r];
NSLog(@"111== %@",r);
*/
/**
+(NSValue *) valueWithPoint:(NSPoint) point;
+(NSValue *) valueWithSize:(NSSize) size;
+(NSValue *) valueWithRect:(NSRect) rect;
-(NSPoint) pointValue;
-(NSSize) sizeValue;
-(NSRect) rectValue;
*/
//NSNull
/*
*+(NSNull *) null;
*/
[mutableDic setObject:[NSNull null] forKey:@"fax"];
id fax;
fax=[mutableDic objectForKey:@"fax"];
if(fax==[NSNull null]){
NSLog(@"pppppppppppppppppp");
}
[pool drain];
return 0;
}
记录一个很简单的小问题
截取字符串有如下方法
[string substringToIndex:7];//截取掉下标7之后的字符串
[string substringFromIndex:2];//截取掉下标2之前的字符串
[string substringWithRange:range];//截取范围类的字符串
遇到一个问题,
如何直接截取某串字符串的后8位??
[string substringFromIndex:string.length- 8 ];
