NSString类的相关用法

一、NSString字符串连接
NSString* string; // 结果字符串

NSString* string1, string2; //已存在的字符串

1. string = [NSString initWithFormat:@"%@,%@", string1, string2 ];
2. string = [string1 stringByAppendingString:string2];</p>
3 . string = [string stringByAppendingFormat:@"%@,%@",string1, string2];

4 . string = [string stringByAppendingFormat:@"%@%@%@%@%@%@",string1, string2, string3, string4......];

可以拼接很多,%@中间加逗号字符串里也带逗号

 

 

二、NNString用法

 

-----创建字符串的方法-----
//1、创建常量字符串
    NSString *astring = @"This is a String!";  
//2、先创建一个空的字符串,然后赋值;
//    alloc和init组合则适合在函数之间传递参数,用完之后需要手工release
    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、创建临时字符串
    NSString *astring;
    astring = [NSString stringWithCString:"This is a temporary string"];
    NSLog(@"astring:%@",astring);
// OR
    NSString *  scriptString = [NSString stringWithString:@" tell application \"Mail\"\r"];
//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];

-----从文件读取字符串-----
    NSString *path = @"astring.text";
    NSString *astring = [[NSString alloc] initWithContentsOfFile:path];
    NSLog(@"astring:%@",astring);
    [astring release];

-----写字符串到文件----    
    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-----
//1、用C比较:strcmp函数
    char string1[] = "string!";
    char string2[] = "string!";
    if(strcmp(string1, string2) = = 0)
    {
        NSLog(@"1");
    }
 //2、isEqualToString方法   
    NSString *astring01 = @"This is a String!";
    NSString *astring02 = @"This is a String!";
    BOOL result = [astring01 isEqualToString:astring02];
    NSLog(@"result:%d",result);
//3、compare方法(comparer返回的三种值:NSOrderedSame,NSOrderedAscending,NSOrderedDescending)   
    NSString *astring01 = @"This is a String!";
    NSString *astring02 = @"This is a String!";   
    BOOL result = [astring01 compare:astring02] = = NSOrderedSame;   //NSOrderedSame 判断两者是否相同
    NSLog(@"result:%d",result);   

    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)
 //4、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)
//5、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。

三、打印日志

    NSLog(@"%@ ",order);//打印字典

    NSLog(@"%@ ",imageUrlString);

posted on 2016-04-09 23:55  洛易  阅读(179)  评论(0编辑  收藏  举报