objective-c 中数据类型之四 字典（NSDictionary）

// 1. 字典初始化、赋值方式1
NSMutableDictionary *m_dictionary = [[NSMutableDictionary alloc] initWithCapacity:0];
[m_dictionary setObject:@1 forKey:@"语文"];
[m_dictionary setObject:@2 forKey:@"数学"];
[m_dictionary setObject:@3 forKey:@"英语"];
// 字典初始化、赋值方式2
NSDictionary *dict1 = @{@"语文": @1, @"数学": @2, @"英语": @3};
m_dictionary = [NSMutableDictionary dictionaryWithDictionary:dict1];

// 字典初始化、赋值方式3
m_dictionary = [NSMutableDictionary dictionaryWithObjectsAndKeys: @1, @"语文", @2, @"数学", @3, @"英语", nil];
// 字典初始化、赋值方式4
m_dictionary = [NSMutableDictionary dictionaryWithObjects:@[@1, @2, @3] forKeys:@[@"语文", @"数学", @"英语"]];
// 赋值方式5
NSDictionary *dict2 = @{ @"物理": @4};
[m_dictionary addEntriesFromDictionary:dict2];

// 2. 排序 方式1
NSArray *sortedKeysArray =
[m_dictionary keysSortedByValueUsingSelector:@selector(compare:)];
// sortedKeysArray (语文, 数学, 英语, 物理)
// 方式2
NSArray *blockSortedKeys = [m_dictionary keysSortedByValueUsingComparator: ^(id obj1, id obj2) {
return [obj1 compare:obj2];
}];
// blockSortedKeys (语文, 数学, 英语, 物理)