平常自動(dòng)布局的時(shí)候基本都是用masonry來(lái)布局,所以經(jīng)常會(huì)用到像下面這樣的代碼.
make.left.right.bottom.mas_equalTo(self);
像這樣一直通過(guò)(.)來(lái)調(diào)用方法,將代碼連成一行,這就是所謂的鏈?zhǔn)骄幊?
那鏈?zhǔn)骄幊痰膬?nèi)部是怎樣實(shí)現(xiàn)的呢?其實(shí)思考一下,無(wú)非就是把當(dāng)前對(duì)象self返回回來(lái),才能繼續(xù)用(.)來(lái)調(diào)用方法.
點(diǎn)進(jìn)去masonry的源碼可以看到,確實(shí)是這樣做的.
WX20170728-111228.png
多的代碼我在這就不貼了,有興趣的自己點(diǎn)進(jìn)去源碼,打斷點(diǎn)一步一步的走就行了.其實(shí)是懶得截圖了T_T T_T ...
那么既然知道了原理是怎么回事,自己來(lái)實(shí)現(xiàn)一樣的鏈?zhǔn)骄幊叹筒浑y了.那么下面就自己來(lái)實(shí)現(xiàn)一下鏈?zhǔn)骄幊?直接上代碼..
@class Test;
typedef Test *(^eatBlock)(NSString *food,void(^)(NSString *food));
@interface Test : NSObject
/**
返回值為一個(gè)block,該block為一個(gè)==>帶兩個(gè)參數(shù)且返回值為self的block
第一個(gè)參數(shù):metter
第二個(gè)參數(shù):void(^)(float metter)),改參數(shù)為一個(gè)==>帶一個(gè)參數(shù)metter且返回值為空的block
*/
- (Test *(^)(float metter,void(^)(float metter)))run;
//同上
- (eatBlock)eat;
@end
方法的實(shí)現(xiàn):
@implementation Test
#pragma mark **************************************************
#pragma mark -- 點(diǎn)語(yǔ)法 - 傳入?yún)?shù)种远，內(nèi)部自己處理哼丈，返回參數(shù)舔示，自己決定做什么
/**
返回值為一個(gè)block,該block為一個(gè)==>帶兩個(gè)參數(shù)且返回值為self的block
第一個(gè)參數(shù):metter
第二個(gè)參數(shù):void(^)(float metter)),改參數(shù)為一個(gè)==>帶一個(gè)參數(shù)metter且返回值為空的block
*/
- (Test *(^)(float metter,void(^)(float metter)))run
{
Test *(^runBlock)(float metter,void(^)(float metter)) = ^(float metter,void(^inBlock)(float metter)){
if (inBlock) {
inBlock(metter);
}
return self;
};
return runBlock;
}
- (eatBlock)eat
{
eatBlock eb = ^(NSString *food,void(^inBlock)(NSString *food)){
if (inBlock) {
inBlock(food);
}
return self;
};
return eb;
}
@end
好了,然后我們就可以開(kāi)始調(diào)用了.
#import "ViewController.h"
#import "Test.h"
@interface ViewController ()
@property (nonatomic,strong)Test *test;
@end
@implementation ViewController
- (void)viewDidLoad {
[super viewDidLoad];
// Do any additional setup after loading the view, typically from a nib.
self.test = [[Test alloc]init];
}
- (void)touchesBegan:(NSSet<UITouch *> *)touches withEvent:(UIEvent *)event
{
self.test.run(100,^(float metter){
NSLog(@"跑了%.2f公里",metter);
}).eat(@"手抓餅",^(NSString *food){
NSLog(@"吃了%@",food);
});
/**
方法調(diào)用拆解如下:
self.test.run ==>返回一個(gè)block
self.test.run(參數(shù)) ==>調(diào)用block,因?yàn)樵揵lock的返回了test對(duì)象,所以可以一直.下去
self.test.run(參數(shù)).eat(參數(shù)).method(參數(shù)).method2(參數(shù));
*/
}
@end
控制臺(tái)輸出
AD444950-0B7C-4025-BF1B-DB472CC1F18D.png
到這,我們就自己實(shí)現(xiàn)了所謂的鏈?zhǔn)骄幊?注釋什么的應(yīng)該寫(xiě)的挺清楚的啦.
