NSString*title = @".....";
NSMutableString *targerStr = [[NSMutableString alloc] initWithString:title ];
[targerStr insertString:@"hello" atIndex:1];
title = targerStr;
NSString*title = @".....";
NSMutableString *targerStr = [[NSMutableString alloc] initWithString:title ];
[targerStr insertString:@"hello" atIndex:1];
title = targerStr;