获取NSString子字符串

NSString类中提供了这样三个方法用于获取子字符串：

• –substringFromIndex:
• –substringWithRange:
• –substringToIndex：

它们该怎么使用呢？见下面代码即可知道。

NSString*str =@"12345";

// NSString *subString0 = [str substringFromIndex:-1];//会放生越界错误

NSString*subString1 = [strsubstringFromIndex:0]; //@"12345"

NSString*subString2 = [strsubstringFromIndex:1]; //@"2345"

NSString*subString3 = [strsubstringFromIndex:4]; //@"5"

NSString*subString4 = [strsubstringFromIndex:5]; //@""

// NSString *subString5 = [str substringFromIndex:6]; //会放生越界错误

// NSString *subString10 = [str substringToIndex:-1]; //会放生越界错误

NSString*subString11 = [strsubstringToIndex:0]; //@"“

NSString*subString12 = [strsubstringToIndex:1]; //@"1”

NSString*subString13 = [strsubstringToIndex:4]; //@"1234“

NSString*subString14 = [strsubstringToIndex:5]; //@"12345”

// NSString *subString15 = [str substringToIndex:6]; //会放生越界错误

NSRangerange1 =NSMakeRange(-1,5);

NSRangerange2 =NSMakeRange(0,6);

NSRangerange3 =NSMakeRange(0,5);

NSRangerange4 =NSMakeRange(1,4);

NSRangerange5 =NSMakeRange(0,0);

NSRangerange6 =NSMakeRange(4,1);

//NSString *subString31 = [str substringWithRange:range1]; //会放生越界错误

//NSString *subString32 = [str substringWithRange:range2]; //会放生越界错误

NSString*subString33 = [strsubstringWithRange:range3]; //@"12345“

NSString*subString34 = [strsubstringWithRange:range4]; //@"2345”

NSString*subString35 = [strsubstringWithRange:range5]; //@"”

NSString*subString36 = [strsubstringWithRange:range6]; //@"5”