Object-c字符串操作

字符串操作：

-(void) testString{
    NSString *str1 = @"some string";
    NSLog(@"%@", str1);

    //格式化字符串
    NSString *str2 = [NSString stringWithFormat:@"%@ %@", @"hello", @123];
    NSLog(@"%@", str2);

    //获取以数字开头的字符串的数字
    NSString *str3 = @“124.3abc12";
    double temp1 = [str3 floatValue];
    NSInteger temp2 = [str3 integerValue];
    NSLog(@"%f", temp1);
    NSLog(@"%lu", temp2);

    //获取字符串长度
    NSUInteger len = [str3 length];
    NSLog(@"%lu", len);

    //比较字符串
    NSString *str4 = @“124.3abC12";
    BOOL isEqual = [str3 isEqualToString:str4];
    NSLog(@"%hhd", isEqual);
    //比较字符串（不区分大小写）
    isEqual = ([str3 caseInsensitiveCompare:str4] == NSOrderedSame);
    NSLog(@"%ld", (long)[str3 caseInsensitiveCompare:str4]);
    NSLog(@"%hhd", isEqual);

    //将字符串全部字符转换为大写字符
    str4 = [str4 uppercaseString];
    NSLog(@"%@", str4);
    //将字符串全部字符转换为小写字符

    str4 = [str4 lowercaseString];
    NSLog(@"%@", str4);

    //去除字符串空字符
    NSString *str5 = @"   one two three   ";
    //去除字符串空字符，包括前后空格，换行符
    str1 = [str5 stringByTrimmingCharactersInSet:[NSCharacterSet whitespaceAndNewlineCharacterSet]];
    //去除字符串空字符，包括前后空格

    str2 = [str5 stringByTrimmingCharactersInSet:[NSCharacterSet whitespaceCharacterSet]];
    NSLog(@"%@",str1);
    NSLog(@"%@",str2);

    //获得substring
    str3 = [str1 substringToIndex:3];
    str4 = [NSString stringWithFormat:@"%@%@",[str2 substringFromIndex:4], @"111" ];
    NSLog(@"%@", str3);
    NSLog(@"%@", str4);
    //分割字符串
    NSArray *arr = [str1 componentsSeparatedByString:@" "];
    NSLog(@"%@", arr);
}

对应输出结果：

2016-05-06 11:09:02.607 test2[65452:7163888] some string
2016-05-06 11:09:02.607 test2[65452:7163888] hello 123
2016-05-06 11:09:02.608 test2[65452:7163888] 124.300003
2016-05-06 11:09:02.608 test2[65452:7163888] 124
2016-05-06 11:09:02.608 test2[65452:7163888] 10
2016-05-06 11:09:02.608 test2[65452:7163888] 0
2016-05-06 11:09:02.608 test2[65452:7163888] 0
2016-05-06 11:09:02.608 test2[65452:7163888] 1
2016-05-06 11:09:02.608 test2[65452:7163888] 124.3ABC12
2016-05-06 11:09:02.608 test2[65452:7163888] 124.3abc12
2016-05-06 11:09:02.608 test2[65452:7163888] one two three
2016-05-06 11:09:02.608 test2[65452:7163888] one two three
2016-05-06 11:09:02.608 test2[65452:7163888] one
2016-05-06 11:09:02.608 test2[65452:7163888] two three111
2016-05-06 11:09:02.608 test2[65452:7163888] (
    one,
    two,
    three
)