NSString賦值方法

　　//1、建立常量字串。    NSString *astring = @"This is a String!";     //2、建立Null 字元串，給予賦值。     NSString *astring = [[NSString alloc] init];    astring = @"This is a String!";    NSLog(@"astring:%@",astring);  　[astring release]; 　　//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、用標準c建立字串:initWithCString方法     char *Cstring = "This is a String!";    NSString *astring = [[NSString alloc] initWithCString:Cstring];    NSLog(@"astring:%@",astring);    [astring release];     //5、建立格式化字串:預留位置（由一個%加一個字元組成）     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、建立臨時字串     NSString *astring;    astring = [NSString stringWithCString:"This is a temporary string"];    NSLog(@"astring:%@",astring);     NSString *path = @"astring.text";    NSString *astring = [[NSString alloc] initWithContentsOfFile:path];    NSLog(@"astring:%@",astring);    [astring release];