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<span style="font-size:24px;"> 1.方法与顺序无关
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2.枚举绑定数据类型
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enum {
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ObjectiveC,
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Java,
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Ruby,
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Python,
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Erlang
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};
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typedef NSUInteger Language;
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3. 属性不用写@synthesize
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4.语法简化
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4.1 NSNumber
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NSNumber *value;
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value = @12345;
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value = @123.45f;
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value = @123.45;
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value = @YES;
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4.2 NSArray
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NSArray *array;
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array = @[]; //空数组
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array = @[ a ]; //一个对象的数组
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array = @[ a, b, c ]; //多个对象的数组
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4.3 NSDictionary
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NSDictionary *dict;
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dict = @{}; //空字典
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dict = @{ k1 : o1 }; //包含一个键值对的字典
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dict = @{ k1 : o1, k2 : o2, k3 : o3 }; //包含多个键值对的字典
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注:对可变的容器,可以用:
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NSMutableArray *mutablePlanets = [@[
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@"Mercury", @"Venus", @"Earth",
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@"Mars", @"Jupiter", @"Saturn",
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@"Uranus", @"Neptune"
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] mutableCopy];
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5.对象下标
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可以通过下标方式存取数组和字典的数据,类似C语言结构
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5.1 NSArray
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NSArray *array = @[ a, b, c ];
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id obj = array[i]; //通过下标方式获取数组对象,替换原有写法:array objectAtIndex:i];
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array[i] = newObj; //也可以直接为数组对象赋值。替换原有写法:[array replaceObjectAtIndex:i withObject:newObj];
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5.2 NSDictionary
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NSDictionary *dict = @{ k1 : o1, k2 : o2, k3 : o3 };
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id obj = dict[k2]; //获取o2对象,替换原有写法:[dic objectForKey:k2];
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dic[k2] = newObj; //重新为键为k2的对象赋值,替换原有写法:[dic setObject:newObj forKey:k2]
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6.小结
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@# nsnumbers
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@{} dictionaries
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@“” strings
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@[] arrays
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@() expressions </span>