[BS-02] iOS数组、字典、NSNumber 新写法—— @[]、@{}

IOS数组、字典、NSNumber 新写法—— @[]、@{}

 

//标准写法
NSNumber * number = [NSNumber numberWithInt:1]; 
NSArray * array = [NSArray arrayWithObjects:@"one", @"two", nil]; 
NSDictionary * dict = [NSDictionary dictionaryWithObjectsAndKeys:@"value1", @"key1", @"value2", @"key2", nil]; 


//快捷写法
NSNumber * number = @1; 
NSArray * array = @[@"one", @"two"]; 
NSDictionary * dict = @{@"key1":@"value1", @"key2":@"value2"}; 

NSMutableArray *m_array = [@[] mutableCopy]; 
NSMutableDictionary *m_dict = [@{} mutableCopy]; 

WWDC2012大会上介绍了大量Objective-C的新特性，能够帮助iOS程序员更加高效地编写代码。在XCode4.4版本中可以使用以下特性：

一. 
Object Literals这个是我认为最赞的一个改进。Object Literals允许你方便地定义数字、数组和字典对象。这个功能类似于java5提供的auto boxing功能。这虽然是一个语法糖，但我认为对提高写代码效率帮助很大。让我们先来看看以前定义数字、数组和字典对象的方法：

1  NSNumber * number = [NSNumber numberWithInt:1];
2  NSArray * array = [NSArray arrayWithObjects:@"one", @"two", nil];
3  NSDictionary * dict = [NSDictionary dictionaryWithObjectsAndKeys:@"value1", @"key1", @"value2", @"key2", nil];

是不是很恶心？现在以上代码可以简化成以下形式，注意到没有，不用再在参数的最后加恶心的nil了，字典的key和value也不再是倒着先写value,再写key了：
1  NSNumber * number = @1;
2  NSArray * array = @[@"one", @"two"];
3  NSDictionary * dict = @{@"key1":@"value1", @"key2":@"value2"};

更多的示例如下：

1  // 整数
2  NSNumber *fortyTwo = @42;             // 等价于 [NSNumber numberWithInt:42]
3  NSNumber *fortyTwoUnsigned = @42U;    // 等价于 [NSNumber numberWithUnsignedInt:42U]
4  NSNumber *fortyTwoLong = @42L;        // 等价于 [NSNumber numberWithLong:42L]
5  NSNumber *fortyTwoLongLong = @42LL;   // 等价于 [NSNumber numberWithLongLong:42LL]
6
7  // 浮点数
8  NSNumber *piFloat = @3.141592654F;    // 等价于 [NSNumber numberWithFloat:3.141592654F]
9  NSNumber *piDouble = @3.1415926535;   // 等价于 [NSNumber numberWithDouble:3.1415926535]
10
11  // 布尔值
12  NSNumber *yesNumber = @YES;           // 等价于 [NSNumber numberWithBool:YES]
13  NSNumber *noNumber = @NO;             // 等价于 [NSNumber numberWithBool:NO]
14
15  // 空数组
16  NSArray * array = @[];                // 等价于 [NSArray array]
17  // 空的字典
18  NSDictionary * dict = @{};            // 等价于 [NSDictionary dictionary]

怎么样？是不是简单多了？而且，为了方便你的旧代码迁移到新的写法，xcode专门还提供了转换工具，在xcode4.4中，选择 Edit -> Refactor -> Convert to Modern Objective-C Syntax即可。

二. 
在XCode4.5中实现了一个很体贴的语法，它允许你使用中括号[]来代替原本的方法来获取get和设置set数组/字典元素。

简单来说，以前的 [array objectAtIndex:idx] 和 [array replaceObjectAtIndex:idx withObject:obj]，可以直接写作 array[idx] 和 array[idx] = obj了。其实这个特性在很多高级语言中都实现了，只是Objective-C生于80年代，一直没改进这个。

使用【】访问数组、字典，使用@()作为计算表达式
1  NSArray * array = @[ @"111", @"222", @"333"];
2  for (int i = 0; i < 3; ++i) {
3      NSLog(@"array[i] = %@", array[i]);
4  }
5  
6  NSMutableDictionary * dict =[@{  @1: @"value1",
7                                   @2: @"value2",
8                                   @3: @"value3" } mutableCopy];
9  for (int i = 0; i < 3; ++i) {
10      NSLog(@"dict[%d] = %@", i, dict[@(i+1)]); //@()是计算表达式
11      dict[@(i+1)] = [NSString stringWithFormat:@"new %@", dict[@(i+1)]];
12  }
13  
14  [dict enumerateKeysAndObjectsUsingBlock:^(id key, id obj, BOOL *stop) {
15      NSLog(@"dict[%@] = %@", key, dict[key]);
16  }];

使用【】对可变数组和可变字典设值：
NSMutableArray *arrayM = [NSMutableArray array];
//NSMutableArray * arrayM = @[ @"111" mutableCopy];//从不可变数组创建可变数组
array[0] = @"123";
array[1] = @"456";

NSMutableDictionary *dictM = [NSMutableDictionary dictionary];
dictM[@"1"] = @"abc";
dictM[@"2"] = @"xyz";

三、遍历元素

你是如何遍历数组的元素的？通常我们有2种做法，一种是用 for in，另一种是用一个变量来循环数组下标。如下：
1    NSArray * array = @[@"123",@"abc",@"xyz"];
2    for (NSString * str in array) {
3       // ...
4    }
5    for (int i = 0; i < array.count; ++i) {
6        NSString * str = [array objectAtIndex:i];
7        ...
8    }

如果是字典，遍历的代码就要稍微复杂一点了：
1    NSDictionary * dict = @{@"1":@"abc",@"2":@"xyz"};
2    NSArray * keys = [dict allKeys];
3    for (NSString * key in keys) {
4        NSString * value = [dict objectForKey:key];
5    }
现在，xcode对于iOS4.0以上的系统，支持用block来遍历元素了。用block来遍历字典可以简化代码的编写，建议大家都使用上这个新特性。
1 [array enumerateObjectsUsingBlock:^(NSString * obj, NSUInteger idx, BOOL *stop) {
2 
3 }];

4 
5 [dict enumerateKeysAndObjectsUsingBlock:^(id key, id obj, BOOL *stop) {
6 
7 }];

 

//  ios 字符串 数组 字典 常用方法

/*
NSString
*/
//一、NSString
/----------------创建字符串的方法----------------/

//1、创建常量字符串。
NSString *astring = @"This is a String!";

//2、创建空字符串，给予赋值。

NSString *astring = [[NSString alloc] init];
astring = @"This is a String!";
[astring release];
NSLog(@"astring:%@",astring);

//3、在以上方法中，提升速度:initWithString方法

NSString *astring = [[NSString alloc] initWithString:@"This is a String!"];
NSLog(@"astring:%@",astring);
[astring release];

//4、用标准c创建字符串:initWithCString方法

char Cstring = "This is a String!";
NSString astring = [[NSString alloc] initWithCString:Cstring];
NSLog(@"astring:%@",astring);
[astring release];

//5、创建格式化字符串:占位符（由一个%加一个字符组成）

int i = 1;
int j = 2;
NSString *astring = [[NSString alloc] initWithString:[NSString stringWithFormat:@"%d.This is %i string!",i,j]];
NSLog(@"astring:%@",astring);
[astring release];

//6、创建临时字符串

NSString *astring;
astring = [NSString stringWithCString:"This is a temporary string"];
NSLog(@"astring:%@",astring);

/----------------从文件读取字符串:initWithContentsOfFile方法----------------/

NSString path = @"astring.text";
NSString astring = [[NSString alloc] initWithContentsOfFile:path];
NSLog(@"astring:%@",astring);
[astring release];

/----------------写字符串到文件:writeToFile方法----------------/

NSString astring = [[NSString alloc] initWithString:@"This is a String!"];
NSLog(@"astring:%@",astring);
NSString path = @"astring.text";
[astring writeToFile: path atomically: YES];
[astring release];

/----------------比较两个字符串----------------/

//用C比较:strcmp函数

char string1[] = "string!";
char string2[] = "string!";
if(strcmp(string1, string2) = = 0)
{
NSLog(@"1");
}

//isEqualToString方法
NSString astring01 = @"This is a String!";
NSString astring02 = @"This is a String!";
BOOL result = [astring01 isEqualToString:astring02];
NSLog(@"result:%d",result);

//compare方法(comparer返回的三种值)
NSString astring01 = @"This is a String!";
NSString astring02 = @"This is a String!";
BOOL result = [astring01 compare:astring02] = = NSOrderedSame;
NSLog(@"result:%d",result);
//NSOrderedSame判断两者内容是否相同

NSString astring01 = @"This is a String!";
NSString astring02 = @"this is a String!";
BOOL result = [astring01 compare:astring02] = = NSOrderedAscending;
NSLog(@"result:%d",result);
//NSOrderedAscending判断两对象值的大小(按字母顺序进行比较，astring02大于astring01为真)

NSString astring01 = @"this is a String!";
NSString astring02 = @"This is a String!";
BOOL result = [astring01 compare:astring02] = = NSOrderedDescending;
NSLog(@"result:%d",result);
//NSOrderedDescending判断两对象值的大小(按字母顺序进行比较，astring02小于astring01为真)

//不考虑大小写比较字符串1
NSString astring01 = @"this is a String!";
NSString astring02 = @"This is a String!";
BOOL result = [astring01 caseInsensitiveCompare:astring02] = = NSOrderedSame;
NSLog(@"result:%d",result);
//NSOrderedDescending判断两对象值的大小(按字母顺序进行比较，astring02小于astring01为真)

//不考虑大小写比较字符串2
NSString astring01 = @"this is a String!";
NSString astring02 = @"This is a String!";
BOOL result = [astring01 compare:astring02
options:NSCaseInsensitiveSearch | NSNumericSearch] = = NSOrderedSame;
NSLog(@"result:%d",result);

//NSCaseInsensitiveSearch:不区分大小写比较 NSLiteralSearch:进行完全比较，区分大小写 NSNumericSearch:比较字符串的字符个数，而不是字符值。

/----------------改变字符串的大小写----------------/

NSString string1 = @"A String";
NSString string2 = @"String";
NSLog(@"string1:%@",[string1 uppercaseString]);//大写
NSLog(@"string2:%@",[string2 lowercaseString]);//小写
NSLog(@"string2:%@",[string2 capitalizedString]);//首字母大小

/----------------在串中搜索子串----------------/

NSString string1 = @"This is a string";
NSString string2 = @"string";
NSRange range = [string1 rangeOfString:string2];
int location = range.location;
int leight = range.length;
NSString *astring = [[NSString alloc] initWithString:[NSString stringWithFormat:@"Location:%i,Leight:%i",location,leight]];
NSLog(@"astring:%@",astring);
[astring release];

/----------------抽取子串 ----------------/

//-substringToIndex: 从字符串的开头一直截取到指定的位置，但不包括该位置的字符
NSString string1 = @"This is a string";
NSString string2 = [string1 substringToIndex:3];
NSLog(@"string2:%@",string2);

//-substringFromIndex: 以指定位置开始（包括指定位置的字符），并包括之后的全部字符
NSString string1 = @"This is a string";
NSString string2 = [string1 substringFromIndex:3];
NSLog(@"string2:%@",string2);

//-substringWithRange: //按照所给出的位置，长度，任意地从字符串中截取子串
NSString string1 = @"This is a string";
NSString string2 = [string1 substringWithRange:NSMakeRange(0, 4)];
NSLog(@"string2:%@",string2);

//扩展路径

NSString Path = @"~/NSData.txt";
NSString absolutePath = [Path stringByExpandingTildeInPath];
NSLog(@"absolutePath:%@",absolutePath);
NSLog(@"Path:%@",[absolutePath stringByAbbreviatingWithTildeInPath]);

//文件扩展名
NSString *Path = @"~/NSData.txt";
NSLog(@"Extension:%@",[Path pathExtension]);

/*
NSMutableString
*/

/---------------给字符串分配容量----------------/
//stringWithCapacity:
NSMutableString *String;
String = [NSMutableString stringWithCapacity:40];

/---------------在已有字符串后面添加字符----------------/

//appendString: and appendFormat:

NSMutableString String1 = [[NSMutableString alloc] initWithString:@"This is a NSMutableString"];
//[String1 appendString:@", I will be adding some character"];
[String1 appendFormat:[NSString stringWithFormat:@", I will be adding some character"]];
NSLog(@"String1:%@",String1); /

/--------在已有字符串中按照所给出范围和长度删除字符------/
/
//deleteCharactersInRange:
NSMutableString String1 = [[NSMutableString alloc] initWithString:@"This is a NSMutableString"];
[String1 deleteCharactersInRange:NSMakeRange(0, 5)];
NSLog(@"String1:%@",String1);

/--------在已有字符串后面在所指定的位置中插入给出的字符串------/

//-insertString: atIndex:
NSMutableString *String1 = [[NSMutableString alloc] initWithString:@"This is a NSMutableString"];
[String1 insertString:@"Hi! " atIndex:0];
NSLog(@"String1:%@",String1);

/--------将已有的空符串换成其它的字符串------/

//-setString:
NSMutableString *String1 = [[NSMutableString alloc] initWithString:@"This is a NSMutableString"];
[String1 setString:@"Hello Word!"];
NSLog(@"String1:%@",String1);

/--------按照所给出的范围，和字符串替换的原有的字符------/

//-setString:
NSMutableString *String1 = [[NSMutableString alloc] initWithString:@"This is a NSMutableString"];
[String1 replaceCharactersInRange:NSMakeRange(0, 4) withString:@"That"];
NSLog(@"String1:%@",String1);

/-------------判断字符串内是否还包含别的字符串(前缀，后缀)-------------/
//01：检查字符串是否以另一个字符串开头- (BOOL) hasPrefix: (NSString ) aString;
NSString String1 = @"NSStringInformation.txt";
[String1 hasPrefix:@"NSString"] = = 1 ? NSLog(@"YES") : NSLog(@"NO");
[String1 hasSuffix:@".txt"] = = 1 ? NSLog(@"YES") : NSLog(@"NO");

//02：查找字符串某处是否包含其它字符串 - (NSRange) rangeOfString: (NSString *) aString，这一点前面在串中搜索子串用到过;

/*
NSArray
*/

/---------------------------创建数组------------------------------/
//NSArray *array = [[NSArray alloc] initWithObjects:
@"One",@"Two",@"Three",@"Four",nil];

self.dataArray = array;
[array release];

//- (unsigned) Count;数组所包含对象个数；
NSLog(@"self.dataArray cound:%d",[self.dataArray count]);

//- (id) objectAtIndex: (unsigned int) index;获取指定索引处的对象;
NSLog(@"self.dataArray cound 2:%@",[self.dataArray objectAtIndex:2]);

/--------------------------从一个数组拷贝数据到另一数组(可变数级)----------------------------/

//arrayWithArray:
//NSArray array1 = [[NSArray alloc] init];
NSMutableArray MutableArray = [[NSMutableArray alloc] init];
NSArray *array = [NSArray arrayWithObjects:
@"a",@"b",@"c",nil];
NSLog(@"array:%@",array);
MutableArray = [NSMutableArray arrayWithArray:array];
NSLog(@"MutableArray:%@",MutableArray);

array1 = [NSArray arrayWithArray:array];
NSLog(@"array1:%@",array1);

//Copy

//id obj;
NSMutableArray newArray = [[NSMutableArray alloc] init];
NSArray oldArray = [NSArray arrayWithObjects:
@"a",@"b",@"c",@"d",@"e",@"f",@"g",@"h",nil];

NSLog(@"oldArray:%@",oldArray);
for(int i = 0; i < [oldArray count]; i++)
{
obj = [[oldArray objectAtIndex:i] copy];
[newArray addObject: obj];
}
//
NSLog(@"newArray:%@", newArray);
[newArray release];

//快速枚举

//NSMutableArray newArray = [[NSMutableArray alloc] init];
NSArray oldArray = [NSArray arrayWithObjects:
@"a",@"b",@"c",@"d",@"e",@"f",@"g",@"h",nil];
NSLog(@"oldArray:%@",oldArray);

for(id obj in oldArray)
{
[newArray addObject: obj];
}
//
NSLog(@"newArray:%@", newArray);
[newArray release];

//Deep copy

//NSMutableArray newArray = [[NSMutableArray alloc] init];
NSArray oldArray = [NSArray arrayWithObjects:
@"a",@"b",@"c",@"d",@"e",@"f",@"g",@"h",nil];
NSLog(@"oldArray:%@",oldArray);
newArray = (NSMutableArray*)CFPropertyListCreateDeepCopy(kCFAllocatorDefault, (CFPropertyListRef)oldArray, kCFPropertyListMutableContainers);
NSLog(@"newArray:%@", newArray);
[newArray release];

//Copy and sort

//NSMutableArray newArray = [[NSMutableArray alloc] init];
NSArray oldArray = [NSArray arrayWithObjects:
@"b",@"a",@"e",@"d",@"c",@"f",@"h",@"g",nil];
NSLog(@"oldArray:%@",oldArray);
NSEnumerator *enumerator;
enumerator = [oldArray objectEnumerator];
id obj;
while(obj = [enumerator nextObject])
{
[newArray addObject: obj];
}
[newArray sortUsingSelector:@selector(compare:)];
NSLog(@"newArray:%@", newArray);
[newArray release];

/---------------------------切分数组------------------------------/

//从字符串分割到数组－ componentsSeparatedByString:
NSString string = [[NSString alloc] initWithString:@"One,Two,Three,Four"];
NSLog(@"string:%@",string);
NSArray array = [string componentsSeparatedByString:@","];
NSLog(@"array:%@",array);
[string release];

//从数组合并元素到字符串- componentsJoinedByString:
NSArray array = [[NSArray alloc] initWithObjects:@"One",@"Two",@"Three",@"Four",nil];
NSString string = [array componentsJoinedByString:@","];
NSLog(@"string:%@",string);

/*
NSMutableArray
*/
/---------------给数组分配容量----------------/
//NSArray *array;
array = [NSMutableArray arrayWithCapacity:20];

/--------------在数组末尾添加对象----------------/
//- (void) addObject: (id) anObject;
//NSMutableArray *array = [NSMutableArray arrayWithObjects:
@"One",@"Two",@"Three",nil];
[array addObject:@"Four"];
NSLog(@"array:%@",array);

/--------------删除数组中指定索引处对象----------------/
//-(void) removeObjectAtIndex: (unsigned) index;
//NSMutableArray *array = [NSMutableArray arrayWithObjects:
@"One",@"Two",@"Three",nil];
[array removeObjectAtIndex:1];
NSLog(@"array:%@",array);

/-------------数组枚举---------------/
//- (NSEnumerator )objectEnumerator;从前向后
//NSMutableArray array = [NSMutableArray arrayWithObjects:
@"One",@"Two",@"Three",nil];
NSEnumerator *enumerator;
enumerator = [array objectEnumerator];

id thingie;
while (thingie = [enumerator nextObject]) {
NSLog(@"thingie:%@",thingie);
}

//- (NSEnumerator )reverseObjectEnumerator;从后向前
//NSMutableArray array = [NSMutableArray arrayWithObjects:
@"One",@"Two",@"Three",nil];
NSEnumerator *enumerator;
enumerator = [array reverseObjectEnumerator];

id object;
while (object = [enumerator nextObject]) {
NSLog(@"object:%@",object);
}

//快速枚举
//NSMutableArray array = [NSMutableArray arrayWithObjects:
@"One",@"Two",@"Three",nil];
for(NSString string in array)
{
NSLog(@"string:%@",string);
}

/*
NSDictionary
*/

/------------------------------------创建字典------------------------------------/
//- (id) initWithObjectsAndKeys;

//NSDictionary dictionary = [[NSDictionary alloc] initWithObjectsAndKeys:@"One",@"1",@"Two",@"2",@"Three",@"3",nil];
NSString string = [dictionary objectForKey:@"One"];
NSLog(@"string:%@",string);
NSLog(@"dictionary:%@",dictionary);
[dictionary release];

/*
NSMutableDictionary
*/

/------------------------------------创建可变字典------------------------------------/
//创建
NSMutableDictionary *dictionary = [NSMutableDictionary dictionary];

//添加字典
[dictionary setObject:@"One" forKey:@"1"];
[dictionary setObject:@"Two" forKey:@"2"];
[dictionary setObject:@"Three" forKey:@"3"];
[dictionary setObject:@"Four" forKey:@"4"];
NSLog(@"dictionary:%@",dictionary);

//删除指定的字典
[dictionary removeObjectForKey:@"3"];
NSLog(@"dictionary:%@",dictionary);

/*
NSValue（对任何对象进行包装）
*/

/--------------------------------将NSRect放入NSArray中------------------------------------/
//将NSRect放入NSArray中
NSMutableArray array = [[NSMutableArray alloc] init];
NSValue value;
CGRect rect = CGRectMake(0, 0, 320, 480);
value = [NSValue valueWithBytes:&rect objCType:@encode(CGRect)];
[array addObject:value];
NSLog(@"array:%@",array);

//从Array中提取
value = [array objectAtIndex:0];
[value getValue:&rect];
NSLog(@"value:%@",value);

/*
从目录搜索扩展名为jpg的文件
*/

//NSFileManager fileManager = [NSFileManager defaultManager];
NSString home;
home = @"../Users/";

NSDirectoryEnumerator *direnum;
direnum = [fileManager enumeratorAtPath: home];

NSMutableArray *files = [[NSMutableArray alloc] init];

//枚举
NSString *filename;
while (filename = [direnum nextObject]) {
if([[filename pathExtension] hasSuffix:@"jpg"]){
[files addObject:filename];
}
}

//快速枚举
//for(NSString *filename in direnum)
//{
// if([[filename pathExtension] isEqualToString:@"jpg"]){
// [files addObject:filename];
// }
//}
NSLog(@"files:%@",files);

//枚举
NSEnumerator *filenum;
filenum = [files objectEnumerator];
while (filename = [filenum nextObject]) {
NSLog(@"filename:%@",filename);
}

//快速枚举
//for(id object in files)
//{
// NSLog(@"object:%@",object);
//}