string截取和拼接

```

NSString * string = @“11111111111”;

NSString * str1 = [string substringToIndex:3];

NSLog(@"%@",str1);

专门截取字符串的一块从第3位开始，长度为4

NSString * str2 = [string substringWithRange:NSMakeRange(3, 4)];

NSLog(@"%@",str2);

从第七位开始带结束

NSString * str3 = [string substringFromIndex:7];

NSLog(@"%@",str3);

string = [NSString stringWithFormat:@"%@-%@-%@",str1,str2,str3];

NSString *tempA = @"123";

NSString *tempB = @"456";

1，字符串拼接

NSString *newString = [NSString stringWithFormat:@"%@%@",tempA,tempB];

2，字符转int

int intString = [newString intValue];

3，int转字符

NSString *stringInt = [NSString stringWithFormat:@"%d",intString];

4，字符转float

float floatString = [newString floatValue];

5，float转字符

NSString *stringFloat = [NSString stringWithFormat:@"%f",intString];

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

判断字符串是否包含字符

BOOL is = [string containsString:@"%2520"];

/// 替换字符，将字符串中的部分数据换成另一个

/// @param string 要修改的字符串

/// @param num 替换的起始位置

/// @param end 替换的长度

-(NSString *)string:(NSMutableString *)string start:(NSInteger)num end:(NSInteger)end{

NSRangerange =NSMakeRange(num, end);

NSString* str2 =@"";

for(inti =0; i < end; i++) {

str2 = [NSStringstringWithFormat:@"%@*",str2];

}

[stringreplaceCharactersInRange:range withString:str2];

returnstring;

}

```