ios基本语法

1.NSString

//C -> OCchar *cstr = "hello world";NSString *str1 = [NSString stringWithUTF8String:cstr];NSLog(@"str1 = %@", str1);//OC -> CNSString *str2 = @"hello objective-c";const char *cstr1 = [str2 UTF8String];NSLog(@"str2 = %s", cstr1);//格式化字符串int a = 10;int b = 20;NSString *str3 = [NSString stringWithFormat:@"a + b = %d", a+b];NSLog(@"str3 = %@", str3);//拼接字符串NSString *str4 = [str1 stringByAppendingString:str2];NSLog(@"str4 = %@", str4);//将字符串转换成小写NSString *str5 = @"ABCDE";NSString *str6 = [str5 lowercaseString];NSLog(@"str6 = %@", str6);//将字符串转换大写NSString *str7 = @"jackie";NSString *str8 = [str7 uppercaseString];NSLog(@"str8 = %@", str8);

//判读是否存在相应的前缀NSString *str9 = @"prefix";BOOL hasPrefix = [str9 hasPrefix:@"pre"];if (hasPrefix) {NSLog(@"存在相应的前缀");}else{NSLog(@"不存在相应的前缀");}//判断是否存在相应的后缀BOOL hasSuffix = [str9 hasSuffix:@"cn"];if (hasSuffix) {NSLog(@"存在相应的后缀");}else{NSLog(@"不存在相应的后缀");}

//判断两个字符串是否相同NSString *str10 = @"hello";NSString *str11 = @"hello";BOOL isEqual = [str10 isEqualToString:str11];if (isEqual) {NSLog(@"Two strings are equal.");} else {NSLog(@"Two strings are not equal.");}//按指定的字符分割字符串NSString *str12 = @"a,b,c,d,e";NSArray *strArray = [str12 componentsSeparatedByString:@","];for (NSString *str in strArray) {NSLog(@"%@", str);}//按照范围截取字符串NSRange range = NSMakeRange(3, 4);NSString *str13 = [str11 substringWithRange:range];NSLog(@"str13 = %@", str13);//从某一位开始截取，一直截取到字符串的最后NSString *str14 = [str10 substringFromIndex:4];NSLog(@"str14 = %@", str14);

//从头开始截取，截取到指定的某一位NSString *str15 = [str10 substringToIndex:4];NSLog(@"str15 = %@", str15);//将字符串拆分为每一个字符for (int i=0; i<[str10 length]; i++) {NSLog(@"%c", [str10 characterAtIndex:i]);}//查找指定字符串的位置，从头开始查找NSString *str16 = @"ab,cd,ef,ds,gd";NSRange range1 = [str16 rangeOfString:@"ef"];NSLog(@"range1.location = %ld range1.length = %ld", range1.location, range1.length);//替换某一个范围的内容NSString *str17 = @"hello iOS, hello Xcode!";NSString *str18 = [str17 stringByReplacingCharactersInRange:NSMakeRange(0, 5) withString:@"您好"];NSLog(@"str18 = %@", str18);

//替换字符串中指定的字符串NSString *str19 = [str17 stringByReplacingOccurrencesOfString:@"hello" withString:@"您好"];NSLog(@"str19 = %@", str19);

NSString *url = @"www.baidu.com";NSURL *httpURL = [NSURL URLWithString:url];//NSURL *fileURL = [NSURL fileURLWithPath:url];NSString *str20 = [NSString stringWithContentsOfURL:httpURL encoding:NSUTF8StringEncoding error:nil];NSLog(@"str20 = %@", str20);//读取本地文件的内容NSString *str21 = [NSString stringWithContentsOfFile:@"/Users/hello/Documents/study Objective-C Demo/lesson 1/Lesson1/Lesson1/demo.txt" encoding:NSUTF8StringEncoding error:nil];NSLog(@"str21 = %@", str21);//将内容写入到文件NSString *str22 = @"Hello China!Hello Shanghai!";BOOL result = [str22 writeToFile:@"/Users/hello/Documents/study Objective-C Demo/lesson 1/Lesson1/Lesson1/test.txt" atomically:YES encoding:NSUTF8StringEncoding error:nil];if (result) {NSLog(@"写入成功！");} else {NSLog(@"写入失败！");}

2.NSNutableString

//创建可变字符串NSMutableString *mstr = [[NSMutableString alloc] initWithCapacity:10];[mstr setString:@"hello"];//追加字符串[mstr appendString:@" world"];int num = 10;[mstr appendFormat:@" - %d -",num];NSLog(@"mstr = %@", mstr);//替换指定范围的字符串NSRange range3 = [mstr rangeOfString:@"world"];[mstr replaceCharactersInRange:range3 withString:@"iOS"];NSLog(@"mstr = %@", mstr);//指定位置插入字符串[mstr insertString:@"Android and " atIndex:6];NSLog(@"mstr = %@", mstr);//删除指定范围的字符串NSRange range4 = [mstr rangeOfString:@"hello "];[mstr deleteCharactersInRange:range4];NSLog(@"mstr = %@", mstr);

3.NSArray

NSArray *array1 = [[NSArray alloc] initWithObjects:@"1",@"2",@"3",@"4",@"5", nil];//获取数组的长度int count = (int)array1.count;NSLog(@"该数组有%d个元素", count);//判断数组中是否还有“2”这个元素BOOL isHave = [array1 containsObject:@"2"];if (isHave) {NSLog(@"存在");} else {NSLog(@"不存在");}//获取数组中最后一个元素NSString *lastStr = [array1 lastObject];NSLog(@"数组最后一个元素 － %@",lastStr);//获取数组中第一个元素NSString *firstStr = [array1 firstObject];NSLog(@"数组中第一个元素 － %@", firstStr);//获取数组中第三个元素NSString *strOf3 = [array1 objectAtIndex:3];NSLog(@"数组中第三个元素 ＝ %@", strOf3);//数组中元素‘3’的位置int index = (int)[array1 indexOfObject:@"3"];NSLog(@"数组中元素‘3’的位置：%d", index);

//使用普通循环来遍历数组中的每个元素for (int i=0; i<array1.count; i++) {NSString *str = [array1 objectAtIndex:i];NSLog(@"str%d = %@", i, str);}NSLog(@"--------------------------------------");//使用for in迭代输出数组中的元素for (NSString *str in array1) {NSLog(@"str = %@", str);}NSLog(@"--------------------------------------");//使用迭代器来遍历数组中元素NSEnumerator *enumerator = [array1 objectEnumerator];id object;while (object = [enumerator nextObject]) {NSLog(@"str = %@", object);}

4.NSMutableArray

Person *p1 = [[Person alloc] initWithName:@"Kevin"];Person *p2 = [[Person alloc] initWithName:@"Steve"];Person *p3 = [[Person alloc] initWithName:@"Gates"];NSArray *array2 = [[NSArray alloc] initWithObjects:p2,p3, nil];NSMutableArray *array1 = [[NSMutableArray alloc] init];//数组中添加一个元素[array1 addObject:p1];//通过另一个数组给新数组添加元素[array1 addObjectsFromArray:array2];NSLog(@"array1 = %@", array1);//移除数组中的最后一个元素//[array1 removeLastObject];//移除数组中的某一个元素//[array1 removeObject:p2];//删除数组中某一位的元素//[array1 removeObjectAtIndex:0];//删除数组中的所有元素//[array1 removeAllObjects];//交换数组中某两位元素[array1 exchangeObjectAtIndex:0 withObjectAtIndex:1];NSLog(@"array1 = %@", array1);

5.NSDictionary

//创建字典NSDictionary *dict1 = [NSDictionary dictionaryWithObject:@"steve" forKey:@"1"];NSLog(@"dict1 = %@", dict1);NSDictionary *dict2 = [NSDictionary dictionaryWithObjects:[NSArray arrayWithObjects:@"Gates",@"Cook",@"Steve", nil] forKeys:[NSArray arrayWithObjects:@"1",@"2",@"3", nil]];NSLog(@"dict2 = %@", dict2);NSDictionary *dict3 = @{@"1":@"Kevin",@"2":@"Tim",@"3":@"Jack"};NSLog(@"dict3 = %@", dict3);//获取字典的个数int count = (int)[dict2 count];NSLog(@"dict2的元素个数：%d", count);

//根据Key获取ValueNSString *value1 = [dict3 valueForKey:@"3"];NSLog(@"value1 = %@", value1);NSString *value2 = [dict3 objectForKey:@"2"];NSLog(@"value2 = %@", value2);//获取字典中所有的值NSArray *arr1 = [dict3 allValues];NSLog(@"arr1 = %@", arr1);//获取字典中所有的键NSArray *arr2 = [dict3 allKeys];NSLog(@"arr2 = %@", arr2);//遍历字典for (NSString *key in dict3) {NSLog(@"%@ - %@", key, [dict3 valueForKey:key]);}//使用迭代器遍历字典中的键id key;NSEnumerator *en = [dict3 keyEnumerator];while (key = [en nextObject ]) {NSLog(@"key = %@", key);}

6.NSMutableDictionary

//创建可变字典NSMutableDictionary *mdict1 = [[NSMutableDictionary alloc] init];[mdict1 setValue:@"Steve" forKey:@"apple"];[mdict1 setObject:@"Gates" forKey:@"microsoft"];NSLog(@"mdict1 = %@", mdict1);//删除字典中所有的元素//[mdict1 removeAllObjects];//根据键删除字典中的某个元素//[mdict1 removeObjectForKey:@"microsoft"];//根据一组键删除某些元素[mdict1 removeObjectsForKeys:[NSArray arrayWithObjects:@"apple",@"microsoft", nil]];NSLog(@"mdict1 = %@", mdict1);