OC-NSDictionary

#NSDictionary

初始化

//方法一
NSDictionary *dict = [[NSDictionary alloc]initWithObjectsAndKeys:@"value1",@"key1",@"value2",@"key2",nil];
NSLog(@"%@",dict);//Crashes if the number of key-value pairs does not match
//方法二 It can be initialized through an array
NSDictionary*dict2 = [NSDictionary dictionartWithObjects:@[@"value1",@"value2"] forKeys:@[@"key1",@"key2"]];
NSLog(@"%@",dict2);
NSDictionary*dict2 = @{
    @"k1":@"v1",
						@"k2":@"v2"};//注意这里 必须是先k再v

查

//直接通过key值获取val值
NSLog(@“%@”,dict3[@"k2"]);
//直接循环获取key值
for(NSString *string in dict3)
{
    
	NSLog(@"%@ %@",string,dict3[string]);
}
//Get all directly with the arraykey值
NSArray* array = [dict3 allKeys];
NSLog(@"%@",array);// k1,k2
//Get all directly with the arraykey值
NSArray* array1 = [dict3 allValues];
NSLog(@"%@",array1);// v1,v2

NSMutableDictionary

初始化

NSMutableDictionary* dict = [NSMutableDictionary dictionary];
dict[@“k1”] = @“v1”;