OC中的NSString的其他用法

NSLog(@"大写：%@", [str uppercaseString]);NSLog(@"小写:  %@", [str lowercaseString]);NSLog(@"首字母大写, 其他字母变小写", [@"aGe", capitalizedString]);BOOL result = [@"abc" isEqualToString:@"Abc"]; //返回0, 即为false//比较字符串大小. compare会返回3个值中的其中一个//1. NSOrderedSame  右边的字符串比左边大//2. NSOrderedAscending  两个字符串的内容相同//3. NSOrderedDescending  左边的字符串比右边的大NSComparisonResult result2 = [@"abc" compare:@"Abc"];if (result2 == NSOrderedSame){  NSLog(@"两个字符串内容相同");}else if (result2 == NSOrderedAscending){  NSLog(@"右边 > 左边");}else if (result2 == NSOrderedDescending){  NSLog(@"右边 < 左边");}//字符串搜索NSString *str = @"12345.txt";//是否以12开头NSLog(@"是否12开头：%i", [str hasPrefix:@12]); //返回1，即trueNSLog(@"是否txt结尾：%i", [str hasSuffix:@"txt"]); //返回1，即true//查找是否包含345字符串, 如果没找到，返回的location=NSNotFound//一旦找到字符串就返回，不理会后续是否还有相同的字符串NSRange range = [str rangeOfString:@"345"];NSLog(@"%@", NSStringFromRange(range));if(range.location == NSNotFound){  NSLog(@"不能找到");}NSRange range = [str rangeOfString:@"345" options: NSBackwardSearch];//字符串的截取, 从第4位开始截取字符串NSLog(@"%@", [str substringFromIndex: 3]);NSLog(@"%@", [str substringToIndex: 3]);//截取字符串中间范围, 截取从第3位开始，取3个字符NSRange range = NSMakeRange(3, 3);NSLog(@"%@", [str substringWithRange: range]);//切割字符串，java中的splitNSString *str = @"1,2,3,4,5,6,7";NSArray *array = [str componentsSeparedByString:@","];NSLog(@"%@", array);//拿到array第0个位置的字符串， array: [1,2,3,4,5,6,7]NSString *str3 = [array objectAtIndex:0]; //输出1//文件路径拼接方法NSMutableArray *components = [NSMutableArray array];[components addObject: @"User"];[components addObject: @"MJ"];[components addObject: @"Desktop"];NSString *path = [NSString pathWithComponents:components];NSLog(@"%@", path);  //输出User/MJ/Desktop//切割成数组NSArray *cmps = [path pathComponents];NSLog(@"%@", cmps);//判断是否是绝对路径NSString path = @"users/mj/test";NSLog(@"%i", [path isAbsolutePath]); //输出0，为false//最后一个目录输出NSLog(@"%@", [path lastPathComponent]);//删除最后一个目录NSLog(@"%@", [path stringByDeletingLastPathComponent]);//再最后拼接一个目录NSLog(@"%@", [path stringByAppendingPathComponent:@"abc"]); //输出 users/mj/test/abc//拓展名处理， 获取拓展名NSString *str = @"/user/desktop/test.text"; NSLog(@"%@", [str pathExtension]); //输出text//删除拓展名方法： stringByDeletingPathExtension//拼接拓展名方法： stringByAppendingPathExtension//强转类型NSString *val = @"1";int valint = [val intValue];//计算数字，不是字符数NString *value = @"我是字符串";NSLog("%@", [value length]); //输出5//取得字符串其中某个字符NSLog("%@", [value characterAtIndex: 0]); //输出 "我"//转成C语言中的字符串char *s = [@"abc" UTF8String];