Objective-C個人學習系列(1) NSString NSMutableString

// 字元初始化

void initStaticString(){

    NSString *s1 = @"abc";//[NSString stringWithString:@"abc"];

    NSString *ss1 = [[NSString alloc] initWithString:s1];

    NSString *s2 = [NSString stringWithFormat:@"abcd"];

    NSString *s3 = [NSString stringWithUTF8String:"abcde"];

    NSString *s4 = [NSString stringWithCString:"abc123" encoding:NSUTF8StringEncoding];

    NSString *s5 = [NSString stringWithContentsOfURL:

          [NSURL URLWithString:@"www.baidu.com"]

                encoding:NSUTF8StringEncoding error:nil];

}

// 字元串截取

void mysubString(){

    NSString *str=@"abcdefg123456";

    //計算字元串長度

    unsigned long n = [str length];

    NSLog(@"%ld",n);

    //從第3個位置開始截取，索引從3開始

    NSLog(@"%@",[str substringFromIndex:3]);    //Output:defg123456

    //截取到第3個位置,索引到3-1，不包括3

    NSLog(@"%@",[str substringToIndex:3]);      //Output:abc

    //截取一段字元串，從2開始的5個字元串

    NSRange range = NSMakeRange(2, 5);   //聲明結構體

    NSLog(@"%@",[str substringWithRange:range]);        //Output:cdefg

    //

    NSLog(@"%@",[str substringWithRange:NSMakeRange(2, 5)]);    //Output:cdefg

    NSString *str2=@"1,2,3,a,b,c";

    //字元串分割

    NSArray *array=[str2 componentsSeparatedByString:@","];     //Output:(1,2,3,a,b,c)

    NSLog(@"%@",array);

    NSRange rangeSub = [str rangeOfString:@"defg"];

    //查找子串首字母在父串中的索引位置

    NSLog(@"range.location=%ld",rangeSub.location);     //Output:3

    //查找子串在父串中占的長度，大于0表示找到了，等于0表示沒找到

    NSLog(@"range.length=%ld",rangeSub.length);      //Output:4

}

//可變字元串 NSMutableString

void multalbeString(){

    NSMutableString *mStr = [[NSMutableString alloc] initWithCapacity:0];

    [mStr appendString:@"This is MutableString!"];

    NSLog(@"%@",mStr);                 //Output:This is MutableString!

    //在原字元串後面添加格式化字元串

    [mStr appendFormat:@"My age is %d\n",23];

    NSLog(@"%@",mStr);              //Output:This is MutableString!My age is 23

    //在原字元串指定位置開始插入字元串

    [mStr insertString:@"AAA"atIndex: 8];

    NSLog(@"%@",mStr);              //Output:This is AAAMutableString!My age is 23

    //删除指定範圍内的一個子字元串

    [mStr deleteCharactersInRange:NSMakeRange(0, 5)];

    NSLog(@"%@",mStr);              //Output:is AAAMutableString!My age is 23

    //替換指定範圍内的一個子字元串

    [mStr replaceCharactersInRange:NSMakeRange(3, 3) withString:@"BBB"];

    NSLog(@"%@",mStr);              //Output:is BBBMutableString!My age is 23

}

void stringOther(){

    NSMutableString *mStr = [[NSMutableString alloc] initWithCapacity:0];

    [mStr appendString:@"abc abc abc WO WO WO!"];

    //轉換為大寫，傳回一個大寫的新字元串

    NSString* up = [mStr uppercaseString];

    NSLog(@"up=%@",up);

    NSLog(@"mstr=%@",mStr);

    //轉換為小寫，傳回一個小寫的新字元串

    NSString* low = [mStr lowercaseString];

    NSLog(@"low=%@",low);

    //傳回一個首字母轉換成大寫的字元串

    NSString* Abc = [mStr capitalizedString];

    NSLog(@"Abc=%@",Abc);

}

//判斷字首字尾

void stringPreSuf(){

    NSString* strURL = @"http://www.music.com/10/love.mp3";

    BOOL isHasPrefix = [strURL hasPrefix:@"http://"];

    BOOL hasSuffix = [strURL hasSuffix:@".mp3"];

    NSLog(@"%d",isHasPrefix);

    NSLog(@"%d",hasSuffix);

}

//字元串比較

void stringComare(){

    NSString* s1 = @"abc";

    NSString* ss1 = @"abc";         //此處ss1 s1 指向的是同一個位址

    NSString* s2 = [[NSString alloc]initWithFormat:@"abc"];

    if ([s1 isEqualToString:s2]) {      //比較字元串的值

        NSLog(@"OK!");

    }

    if (s1 == s2) {            //比較字元串的位址，s1==s2 為假 s1==ss1 為真

        NSLog(@"OK!");

    }

    int n = [s1 compare:s2];        //1,0,-1

    NSLog(@"%d",n);

}