NSString

int main(int argc, const char * argv[]) {
//创建一个字符串对象
//字面量方法
NSString *str1 = @”www.hello.text”;
NSLog(@”%@”,str1);
//通过alloc和init创建一个空字符串
NSString *str = [[NSString alloc] init];
NSString *str = @”姗姗来迟”;
NSLog (@”%@”,str);
//系统提供的 便利构造器的方法
NSString *str = [NSString stringWithstring:@”山山来了”];
//求字符串长度
NSLog(@”%ld”,str.length);

//快速创建一个字符串常量
NSString *string1 = @”abc”;
NSString *string2 = @”cde”;
NSLog(@”%@ %@”,string1,string2);
//创建一个格式化的字符串(内存在堆区)
NSString *string3 = [[NSString alloc] initWithFormat:@”整数:%d”,10];
NSString *string4 = [[NSString alloc] initWithFormat:@”浮点数:%f”,10.0];
NSLog(@”%@ %@”,string3,string4);

//字符串比较
NSString *string5 = [NSString stringWithFormat:@”123”];
NSString *string6 = [NSString stringWithFormat:@”124”];
//测试内容是否相等
//方法一
if ([string5 isEqualToString:string6]) {
NSLog(@”same content”);
}else{
NSLog(@”different content”);
}
//方法二
//不区分大小写比较字符串大小
NSString *aString = @”ABC”;
NSString *otherString = @”abc”;
NSComparisonResult rst3 = [aString compare:otherString];
NSLog(@”%ld”,rst3);
//测试内容是否指向同一个对象
if (string5 == string6) {
NSLog(@”same pointer”);
}else{
NSLog(@”difference pointer”);
}

//比较两个字符串的地址是否相同
if(string5 == string6){
}

//比较前缀和后缀
NSString *str = @”douyu”;
NSString *prefix = @”dou”;
NSLog(@”%d”,[str hasPrefix:prefix]);
NSString *suffix = “tv”;
NSLog(@”%d”,[str hasSuffix:suffix]);

//截取字符串中的字符
NSLog(@”%c”,[string6 characterAtIndex:2]);
//字符串转换
NSString *string7 = @”hEllo world”;
NSLog(@”%@”,[string7 uppercaseString]);
NSLog(@”%@”,[string7 lowercaseString]);
NSLog(@”%@”,[string7 capitalizedString]);
//转换成基本数据类型
NSString *string8 = @”3.14”;
float pi = [string8 floatValue];
NSLog(@”%.2f”,pi);
//把OC字符转化为c的字符
const char *p = [string8 UTF8String];
NSLog(@”%c”,*p);
//将字符串转换为数组
NSString *string9 = @”abc bcd xyz”;
NSArray *array = [string9 componentsSeparatedByString:@”“];
NSLog(@”array:%@”,array);

//截取字符串
NSString *string10 = @”abcdefg”;
NSString *substring1 = [string10 substringToIndex:2];
NSLog(@”%@”,substring1);
NSString *substring2 = [string10 substringFromIndex:2];
NSLog(@”%@”,substring2);
//通过范围截取
NSRange range = {4,2};
range.location = 4;
range.length = 2;
NSString *substring3 = [string10 substringWithRange:range];
NSLog(@”%@”,substring3);
//NSMakeRange
NSString *substring4 = [string10 substringWithRange:NSMakeRange(4, 2)];
NSLog(@”%@”,substring4);

//字符串拼接
NSString *string11 = @”abc”;
NSString *string12 = @”xyz”;
NSString *appString1 = [[NSString alloc] initWithFormat:@”%@%@”,string11,string12];
NSString *appString2 = [string11 stringByAppendingString:string12];
NSString *appString3 = [string11 stringByAppendingFormat:@”%@”,string12];
NSLog(@”%@ %@ %@”,appString1,appString2,appString3);

//查找字符串对象
NSString *link = @”abcetarget=_blankxyz”;
//查找字符串,找不到返回
NSRange range1 = [link rangeOfString:@”target=_blank”];
if (range1.location != NSNotFound) {
NSLog(@”location = %ld,length = %ld”,range1.location,range1.length);
}

//可变字符串对象:NSMutableString继承至string
//使用字面的方式创建的是不可变字符串,只能拿不可变的指针来接受
NSMutableString *mutablestring1 = [[NSMutableString alloc] initWithFormat:@”abc”];
NSLog(@”%@”,mutablestring1);
//对可变字符串赋值
[mutablestring1 setString:@”qianfeng”];
NSLog(@”%@”,mutablestring1);
//插入一个字符串,在指定下标(不要越界)位置插入NSString类型字符
[mutablestring1 insertString:@”…xyz” atIndex:3];
NSLog(@”%@”,mutablestring1);
//拼接
[mutablestring1 appendString:@”123”];
NSLog(@”%@”,mutablestring1);
//替换
NSRange range2 = {1,3};
[mutablestring1 replaceCharactersInRange:range2 withString:@”egf”];
NSLog(@”%@”,mutablestring1);
//删除
[mutablestring1 deleteCharactersInRange:range2];
NSLog(@”%@”,mutablestring1);

//练习给定一个图片文件名,判断字符串中是否以“png”结尾,如果是就替换成“jpg”,如果 不是,就拼接”.jpg”。
//给定范围 不可变字符串
NSString *str = @”1232.png”;
if([str hasSuffix:@”png”]){
NSInteger length = str.length;
NSRange range = NsMakeRange (length -3 , 3);
str = [str stringByReplacingCharactersInRange:range withString:@”jpg”];
} else {
str = [str stringByAppedndingString:@”.jpg”];
}
NSlog(@”%@”,str);

//带范围 可变字符串
NSMutableString *str = [[NSMutableString alloc] initWithString:@”000abc”];
if ([str hasSuffix:@”png”]) {
NSInteger length = [str length];
NSRange range = NSMakeRange(length-3, 3);
[str replaceCharactersInRange:range withString:@”jpg”];
}else{
[str appendString:@”.jpg”];
}
NSLog(@”%@”,str);

return 0;

}