OC字符串

/*
// 1 字符串的初始化
NSString *str1 = [[NSString alloc]init];
NSString *str2 = @”abc”;
NSLog(@”str1 = %@ \nstr = %@”,str1,str2);
// 2 基础数据类型－》字符串:参数1:表明参数2的数据类型 参数2:内容
NSString *str3 = [NSString stringWithFormat:@”%d”,1];
NSString *str4 = [NSString stringWithFormat:@”%f”,1.5];
NSLog(@”str3=%@ str4=%@”,str3,str4);
// 3 字符串－》基础数据类型

NSString *str3 = [NSString stringWithFormat:@”%d”,1];
NSString *str4 = [NSString stringWithFormat:@”%f”,1.5];
int a = str3.intValue;
float b = str4.floatValue;
NSLog(@”a=%d b=%f”,a,b);

// 4 字符串的比较
NSString *str1 = [NSString stringWithFormat:@”%@”,@”abc”];
NSString *str2 = @”abc”;
NSString *str3 = [NSString stringWithFormat:@”%@”,@”123″];
if ([str1 isEqualToString:str2]) {//如果相等true
NSLog(@”1 字符串相等”);
}
if (![str1 isEqualToString:str3]) {//如果相等true
NSLog(@”1 字符串不相等”);
}
// 很少
if (str1 == str2) {
NSLog(@”2 字符串相等”);
}else{
NSLog(@”2 字符串不相等”);
}

// 5 字符串的大小写转化
NSString *str1 = @”abCDefg”;
NSLog(@”%@”,[str1 lowercaseString]);// 全部转化为小写
NSLog(@”%@”,[str1 uppercaseString]);// 全部转化为大写
NSLog(@”%@”,[str1 capitalizedString]);// 首字母大写

// 6 NSString NSArray
// 7 字符串的内容索引 012
NSString *str1 = @”abcdefg”;
NSString *str2 = @”cde”;
NSRange rang;//结构体 字符串的长度 和位置
rang = [str1 rangeOfString:str2];
NSLog(@”%lu %lu”,(unsigned long)rang.length,(unsigned long)rang.location);

// 8 字符串的位置索引
NSString *str1 = @”abcdefg”;
NSRange rang;
rang.length = 2;
rang.location = 3;
NSString *str2 = [str1 substringWithRange:rang];
NSLog(@”%@”,str2);

// 9 字符串的增删改查
NSString *str1 = @”abc”;
NSString *str2 = [str1 stringByAppendingString:@”123″];
NSString *str3 = [str2 stringByAppendingFormat:@”%d”,999];
NSLog(@”str2=%@ str3=%@”,str2,str3);
NSString *str4 = [str3 stringByReplacingOccurrencesOfString:@”c123″ withString:@”aa”];
NSString *str5 = [str3 stringByReplacingOccurrencesOfString:@”999″ withString:@””];
NSLog(@”str4=%@ str5=%@”,str4,str5);

// 10 可变字符串
NSMutableString *str6 = [[NSMutableString alloc]init];
[str6 appendString:@”abc”];
[str6 appendString:@”123″];
[str6 insertString:@”hhh” atIndex:3];
[str6 appendFormat:@”%f”,4.5];
NSLog(@”str6=%@”,str6);

// 11 字符串的内容检查
NSString *str1 = @”http://www.imooc.com”;
if ([str1 containsString:@”imooc”]) {
NSLog(@”包含慕课网”);
}
if ([str1 hasPrefix:@”http”]) {
NSLog(@”http”);
}
if ([str1 hasSuffix:@”com”]) {
NSLog(@”com”);
}
*/
// 12 常用技巧
NSString *str1 = @” abc edf “;
NSLog(@”str1=%@”,str1);
NSString *str2 = [str1 stringByTrimmingCharactersInSet:[NSCharacterSet whitespaceCharacterSet]];
NSLog(@”str2=%@”,str2);
NSLog(@”%d %d”,str1.length,str2.length);