componentsJoinedByString 和 componentsSeparatedByString 的方法的区别
将string字符串转换为array数组
NSArray *array = [Str componentsSeparatedByString:@","];
＝＝反向方法
将array数组转换为string字符串
NSString *tempString = [mutableArray componentsJoinedByString:@","];--分隔符
1.字符串的比较
//*****************C字符串的比较
char *p = "jos";
char *q = "ios";
int ret = strcmp(p, q);//ret = p - q
if (ret > 0) {
NSLog(@"p > q");
} else if (ret < 0) {
NSLog(@"p < q");
} else {
NSLog(@"p == q");
}
//*****************比较相等与否
NSString * str1 = @"I love ios";
NSString * str2 = @"I love ios";
if ([str1 isEqualToString:str2]) {
NSLog(@"相等");
}else{
NSLog(@"不相等");
}
//*****************OC字符串比较大小
NSString * str3 = @"how do you do";
NSString * str4 = @"how do you do";
NSComparisonResult result = [str3 compare:str4];
if (result == NSOrderedSame) {
NSLog(@"str3 == str4");
}else if (result == NSOrderedAscending){
NSLog(@"str3 < str4");
}else if (result == NSOrderedDescending){
NSLog(@"str3 > str4");
}
//*****************不区分大小写的比较
NSString * str5 = @"how are you";
NSString * str6 = @"HOW ARE YOU";
NSComparisonResult result1 = [str5 caseInsensitiveCompare:str6];
if (result1 == NSOrderedSame) {
NSLog(@"str5 == str6");
}else if (result1 == NSOrderedAscending){
NSLog(@"str5 < str6");
}else if (result1 == NSOrderedDescending){
NSLog(@"str5 > str6");
}
NSString * str = @"I love iOS";
//小写转大写
NSString * str1 = [str uppercaseString];
//大写转小写
NSString * str2 = [str lowercaseString];
//首字母大写
NSString * str3 = [str capitalizedString];
//字符串范围
NSRange range = [str rangeOfString:@"love"];//空格也要算在内
//位置range.location == 2，长度range.length == 4
//提取字符串（第一个字符的下标是0）
NSString * str4 = [str substringFromIndex:3];//截取从第3个字符开始到结尾（即：ove iOS）
NSString * str5 = [str substringToIndex:5];//截取前5个字符（即：I lov）
NSString * str6 = [str substringWithRange:NSMakeRange(2, 4)];//截取从第2个字符起往后数4个字符（即：love）
//判断字符串首尾
if ([str hasPrefix:@"I love"]) {
NSLog(@"是以I love开头");
}
if ([str hasSuffix:@"iOS"]) {
NSLog(@"是以iOS结尾");
}
//字符串的追加1（追加到尾部）
NSMutableString * mStr1 = [[NSMutableString alloc] initWithString:@"I love iOS"];
[mStr1 appendString:@" very much"];
//结果：mStr1 = @"I love iOS very much"
//字符串的追加2（追加到尾部）
NSMutableString * mStr2 = [[NSMutableString alloc] initWithString:@"I love iOS"];
int i = 2;
[mStr2 appendFormat:@" %d", i];
//结果：mStr2 = @"I love iOS 2�"
//字符串的插入
NSMutableString * mStr3 = [[NSMutableString alloc] initWithString:@"abcdefg"];
[mStr3 insertString:@"yyy" atIndex:3];
//结果：mStr3 = @"abcyyydefg"
//字符串的删除
NSMutableString * mStr4 = [[NSMutableString alloc] initWithString:@"abcdefg"];
[mStr4 deleteCharactersInRange:NSMakeRange(3, 2)];
//结果：mStr4 = @"abcfg"
//字符串的替换
NSMutableString * mStr5 = [[NSMutableString alloc] initWithString:@"abcdefg"];
[mStr5 replaceCharactersInRange:NSMakeRange(0, 2) withString:@"1234"]
//结果：mStr5 = @"1234cdefg"
#创建字典#
NSDictionary *dict = [[NSDictionary alloc] initWithObjectsAndKeys:@"one", @"1", @"two", @"2", @"three", @"3", nil];
#键值对的个数#
NSInteger count = [dict count];
#通过键查找值#
NSString *str = [dict objectForKey:@"two”];
NSString *str = dict[@"two”];
#遍历#
for (NSString *str in dict) {
NSLog(@"%@", str); //遍历的是字典dict中的键
NSLog(@"%@", dict[str]);//遍历的是字典dict中的值
}
#创建可变字典#
NSMutableDictionary * mdict = [[NSMutableDictionary alloc] initWithDictionary:dict];
#增加键值对#
[mdict setObject:@"four" forKey:@"4"];
#删除键值对#
[mdict5 removeObjectForKey:@“4”];//删除单个键
[mdict5 removeAllObjects];//全部删除
#字典替换#
NSDictionary * dict = @{@“3”:@“xixi", @"2":@"gogo"};
[mdict setDictionary:dict];//把字典mdict全部改为字典dict
字符串的拆分(componentsSeparatedByCharactersInSet)
有字符串“A~B^C" ，我拆分为 "A", "B" 和 "C"?
NSString *str = @"A~B^C";
NSArray *arr = [str componentsSeparatedByCharactersInSet: [NSCharacterSet characterSetWithCharactersInString:@"^~"]];
NSLog(@"%@", arr);