objective-c NSString 常用操作
//1、创建常量字符串。
NSString*astring=@"ThisisaString!";
//2、创建空字符串，给予赋值。
NSString*astring=[[NSStringalloc]init];
astring=@"ThisisaString!";
NSLog(@"astring:%@",astring);
[astringrelease];
//3、在以上方法中，提升速度:initWithString方法
NSString*astring=[[NSStringalloc]initWithString:@"ThisisaString!"];
NSLog(@"astring:%@",astring);
[astringrelease];
//4、用标准c创建字符串:initWithCString方法
char*Cstring="ThisisaString!";
NSString*astring=[[NSStringalloc]initWithCString:Cstring];
NSLog(@"astring:%@",astring);
[astringrelease];
//5、创建格式化字符串:占位符（由一个%加一个字符组成）
inti=1;
intj=2;
NSString*astring=[[NSStringalloc]initWithString:[NSStringstringWithFormat:@"%d.Thisis%istring!",i,j]];
NSLog(@"astring:%@",astring);
[astringrelease];
//6、创建临时字符串
NSString*astring;
astring=[NSStringstringWithCString:"Thisisatemporarystring"];
NSLog(@"astring:%@",astring);
NSString*path=@"astring.text";
NSString*astring=[[NSStringalloc]initWithContentsOfFile:path];
NSLog(@"astring:%@",astring);
[astringrelease];
NSString*astring=[[NSStringalloc]initWithString:@"ThisisaString!"];
NSLog(@"astring:%@",astring);
NSString*path=@"astring.text";
[astringwriteToFile:pathatomically:YES];
[astringrelease];
//用C比较:strcmp函数
charstring1[]="string!";
charstring2[]="string!";
if(strcmp(string1,string2)==0)
{
NSLog(@"1");
}
//isEqualToString方法
NSString*astring01=@"ThisisaString!";
NSString*astring02=@"ThisisaString!";
BOOLresult=[astring01isEqualToString:astring02];
NSLog(@"result:%d",result);
//compare方法(comparer返回的三种值)
NSString*astring01=@"ThisisaString!";
NSString*astring02=@"ThisisaString!";
BOOLresult=[astring01compare:astring02]==NSOrderedSame;
NSLog(@"result:%d",result);
//NSOrderedSame判断两者内容是否相同
NSString*astring01=@"ThisisaString!";
NSString*astring02=@"thisisaString!";
BOOLresult=[astring01compare: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=@"thisisaString!";
NSString*astring02=@"ThisisaString!";
BOOLresult=[astring01compare: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=@"thisisaString!";
NSString*astring02=@"ThisisaString!";
BOOLresult=[astring01caseInsensitiveCompare: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)
//如何判断字符串为空
NSString*urlString=[urlInputstringValue];
if(!urlString){
NSLog(@”NOINPUT.”);
}else{
if([urlStringlength]==0){
NSLog(@”NOINPUT.”);
}else{
}
}
}
ConvertNSStringtoint
1NSString*aNumberString=@"123";
2inti=[aNumberStringintValue];
ConvertinttoNSString
1intaNumber=123;
2NSString*aString=[NSStringstringWithFormat:@"%d",aNumber];