NSRangeFromString和rangeOfString:

今天误把NSRangeFromString当成rangeOfString使用了，发现并不是那么回事，记录一下区别
NSRangeFromString
Returns a range from a textual representation.(翻译过来意思大概是：直接用文本来表示范围)

Discussion

Scans *aString* for two integers which are used as the location and length values, in that order, to create anNSRange struct. If *aString* only contains a single integer, it is used as the location value. If *aString* does not contain any integers, this function returns an NSRange struct whose location and length values are both 0.
（扫描aString作为位置和长度值的两个整数，按顺序创造一个NSRange。如果aString只包含一个整数，则使用它作为location值。如果' aString '不包含任何整数，则此函数返回一个' NSRange '结构体，其位置和长度值均为0。）
举例说明：

NSString *str1 = @"abc";
NSRange range = NSRangeFromString(str1);
NSLog(@"\nlocation:%ld  length:%ld", range.location, range.length);
//location:0  length:0

NSString *str2 = @"1-10";
range = NSRangeFromString(str2);
NSLog(@"\nlocation:%ld  length:%ld", range.location, range.length);
//location:1  length:10

NSString *str3 = @"16";
range = NSRangeFromString(str3);
NSLog(@"\nlocation:%ld  length:%ld", range.location, range.length);
//location:16  length:0

NSString *str4 = @"9 100";
range = NSRangeFromString(str4);
NSLog(@"\nlocation:%ld  length:%ld", range.location, range.length);
//location:9  length:100

NSString *str5 = @"12 16 25";
range = NSRangeFromString(str5);
NSLog(@"\nlocation:%ld  length:%ld", range.location, range.length);
//location:12  length:16

rangeOfString就是常规理解的方式了

NSString *str1 = @"123456789";
NSString *str2 = @"6789";
NSRange range = [str1 rangeOfString:str2];
NSLog(@"\nlocation:%ld  length:%ld", range.location, range.length);
//location:5  length:4

表示str2 在str1中的range。