Objective-C常用代碼

/*******************************************************************************************
    NSString
    *******************************************************************************************/
//一、NSString    
/*----------------創建字符串的方法----------------*/

//1、創建常量字符串。
NSString*astring = @"This is a String!";

//2、創建空字符串，給予賦值。

NSString*astring =[[NSStringalloc]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 =[[NSStringalloc]initWithString:@"This is a String!"];
NSLog(@"astring:%@",astring);
[astring release];

//4、用標準c創建字符串:initWithCString方法

char*Cstring="This is a String!";
NSString*astring =[[NSStringalloc]initWithCString:Cstring];
NSLog(@"astring:%@",astring);
[astring release];

//5、創建格式化字符串:占位符（由一個%加一個字符組成）

int i =1;
int j =2;
NSString*astring =[[NSStringalloc]initWithString:[NSStringstringWithFormat:@"%d.This is %i string!",i,j]];
NSLog(@"astring:%@",astring);
[astring release];

//6、創建臨時字符串

NSString*astring;
   astring =[NSStringstringWithCString:"This is a temporary string"];
NSLog(@"astring:%@",astring);

/*----------------從文件讀取字符串:initWithContentsOfFile方法----------------*/

NSString*path= @"astring.text";
NSString*astring =[[NSStringalloc]initWithContentsOfFile:path];
NSLog(@"astring:%@",astring);
[astring release];

/*----------------寫字符串到文件:writeToFile方法----------------*/

NSString*astring =[[NSStringalloc]initWithString:@"This is a String!"];
NSLog(@"astring:%@",astring);
NSString*path= @"astring.text";
[astring writeToFile:pathatomically:YES];
[astring release];    

/*----------------比較兩個字符串----------------*/

//用C比較:strcmp函數

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返回的三種值)    
NSString*astring01 = @"This is a String!";
NSString*astring02 = @"This is a String!";
BOOL result =[astring01 compare:astring02]== NSOrderedSame;
NSLog(@"result:%d",result);
//NSOrderedSame判斷兩者內容是否相同

NSString*astring01 = @"This is a String!";
NSString*astring02 = @"this is a String!";
BOOL result =[astring01 compare:astring02]== NSOrderedAscending;
NSLog(@"result:%d",result);
//NSOrderedAscending判斷兩對象值的大小(按字母順序進行比較，astring02大于astring01為真)

NSString*astring01 = @"this is a String!";
NSString*astring02 = @"This is a String!";
BOOL result =[astring01 compare:astring02]== NSOrderedDescending;
NSLog(@"result:%d",result);
//NSOrderedDescending判斷兩對象值的大小(按字母順序進行比較，astring02小于astring01為真)

//不考慮大小寫比較字符串1
NSString*astring01 = @"this is a String!";
NSString*astring02 = @"This is a String!";
BOOL result =[astring01 caseInsensitiveCompare:astring02]== NSOrderedSame;
NSLog(@"result:%d",result);
//NSOrderedDescending判斷兩對象值的大小(按字母順序進行比較，astring02小于astring01為真)

//不考慮大小寫比較字符串2
NSString*astring01 = @"this is a String!";
NSString*astring02 = @"This is a String!";
BOOL result =[astring01 compare:astring02
options:NSCaseInsensitiveSearch | NSNumericSearch]== NSOrderedSame;