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  • 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" "];
    //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);

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  • 原文地址:https://www.cnblogs.com/royi123/p/5373131.html
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