1.首字母大写
代码：
//首字母大写
NSString *string = @"ligang";
NSLog(@"string: %@",[string capitalizedString]);
打印：
2015-07-16 23:06:11.652 iOSStrongDemo[10279:3062010] string: Ligang
2.分割字符串
代码：
//分割字符串
NSString *string = @"This is a iOSDevTip";
NSArray *array = [string componentsSeparatedByString:@"a"];
NSString *string1 = [array objectAtIndex:0];
NSString *string2 = [array objectAtIndex:1];
NSLog(@"string1:%@  string2:%@",string1,string2);
打印：
2015-07-16 22:40:39.559 iOSStrongDemo[10165:3055448] string1:This is   string2: iOSDevTip
3.追加字符串
代码：
//追加字符串
NSMutableString *string = [[NSMutableString alloc] initWithString:@"I Love "];
[string appendString:@"China"];
NSLog(@"string:%@",string);
打印：
2015-07-16 22:42:32.305 iOSStrongDemo[10189:3056410] string:I Love China
4.插入字符串
代码：
//插入字符串
NSMutableString *string = [[NSMutableString alloc] initWithString:@"I China"];
[string insertString:@"Love " atIndex:2];
NSLog(@"string: %@",string);
打印：
2015-07-16 22:44:10.706 iOSStrongDemo[10206:3057014] string: I Love China


5.删除字符串
代码：
//删除字符串
NSMutableString *string = [[NSMutableString alloc] initWithString:@"I love China"];
[string deleteCharactersInRange:NSMakeRange(2, 4)];
NSLog(@"String1: %@",string);
打印：
2015-07-16 22:46:58.437 iOSStrongDemo[10219:3057749] String1: I  China
6.判断是否包含前后缀
代码：
//判断是否包含前后缀
NSString *string = @"I love China";
BOOL isHasI = [string hasPrefix:@"I"];
BOOL isHasChina = [string hasSuffix:@"China"];
7.替换字符串
代码：
//替换字符串
NSString *string = @"I love China";
NSString *replaceString = [string stringByReplacingOccurrencesOfString:@"love" withString:@"like"];
NSLog(@"replaceString:  %@",replaceString);
打印：
2015-07-16 22:56:07.405 iOSStrongDemo[10236:3059503] replaceString:  I like China
8.去除字符串首尾的空格和换行符
代码：
//去除字符串首尾的空格和换行符
NSString *string = @" I love China ";
NSString *text = [string stringByTrimmingCharactersInSet:[NSCharacterSet whitespaceAndNewlineCharacterSet]];
NSLog(@"text:%@",text);
打印：
2015-07-16 23:00:47.845 iOSStrongDemo[10265:3061013] text:I love China

总结的不错，收藏了哦

它有这么多功能啊，学习喽