前言
iOS本身不支持链式语法，但了解链式原理后就知道，它其实真的很简单！
想学链式语法的同学一般都已经清楚了它的定义及定位，这里就不多说了，链式最经典的体现莫过于Masnory，在这模仿Masnory用链式语法写了个小demo，看完我这个demo，至少写代码应该没问题了。
废话不多说了，直接上代码（点击下载演示demo）：
实现
整个demo核心其实就四个文件（文中红色区域标注部分），本文主要针对这四个文件展开。
工程目录
1、XRChainMaker
该文件是模仿Masnory中的MASConstraint文件定义的一个文件，功能也和MASConstraint类似，主要用于链式语法的声明和实现，因为本demo是对UIView的一个链式语法封装，所以在该文件中添加了一个全局属性,用于接收继承自UIView的控件，如下。
@property (nonatomic,weak) UIView *originalView;
XRChainMaker.h
这个头文件中被声明的项比较多，在此处为了简单只拿UIButton列举了几项，要看详细的同学请下载demo。
#import <Foundation/Foundation.h>
#import <UIKit/UIKit.h>
@interface XRChainMaker : NSObject
@property (nonatomic,weak) UIView *originalView;
- (XRChainMaker *(^)(id,SEL,UIControlEvents))addAction;
#pragma mark UIButton
// set button title
- (XRChainMaker *(^)(NSString *,UIControlState))title;
// set button title color
- (XRChainMaker *(^)(UIColor *,UIControlState))titleColor;
//set background image
- (XRChainMaker *(^)(UIImage *,UIControlState))bgImage;
// set button title position
- (XRChainMaker *(^)(UIControlContentHorizontalAlignment))horizontalAlignment;
@end
XRChainMaker.m
这部分代码对主要是针对链式语法声明部分的实现，并对全局变量originalView在内部的转换做了个实现，包括如果继承自UIView的控件同一属性赋值方式不同时如何进行转化。
#import "XRChainMaker.h"
@interface XRChainMaker ()
@property (nonatomic,weak) UILabel *label;
@property (nonatomic,weak) UIButton *button;
@property (nonatomic,weak) UITextField *textField;
@property (nonatomic,weak) UITableView *tableView;
@property (nonatomic,weak) UITextView *textView;
@property (nonatomic,retain) UIActivityIndicatorView *spinner;
@end
@implementation XRChainMaker
#pragma mark button
// set button title
- (XRChainMaker *(^)(NSString *,UIControlState))title{
return ^(NSString *title,UIControlState state){
[self.button setTitle:title forState:state];
return self;
};
}
//
- (XRChainMaker *(^)(UIColor *,UIControlState))titleColor{
return ^(UIColor *color,UIControlState state){
[self.button setTitleColor:color forState:state];
return self;
};
}
// set title alignment
- (XRChainMaker *(^)(UIControlContentHorizontalAlignment))horizontalAlignment{
return ^(UIControlContentHorizontalAlignment alignment){
self.button.contentHorizontalAlignment = alignment;
return self;
};
}
- (XRChainMaker *(^)(id,SEL,UIControlEvents))addAction{
return ^(id target,SEL sel ,UIControlEvents event){
[self.button addTarget:target action:sel forControlEvents:event];
return self;
};
}
#pragma mark
- (void)setOriginalView:(UIView *)originalView{
_originalView = originalView;
if ([_originalView isKindOfClass:UILabel.class]) {
_label = (UILabel *)_originalView;
}else if ([_originalView isKindOfClass:UIButton.class]){
_button = (UIButton *)_originalView;
}else if ([_originalView isKindOfClass:UITextField.class]){
_textField = (UITextField *)_originalView;
}else if ([_originalView isKindOfClass:UITextView.class]){
_textView = (UITextView *)_originalView;
}else if ([_originalView isKindOfClass:[UITableView class]]){
_tableView = (UITableView *)_originalView;
}
else if ([_originalView isKindOfClass:UIActivityIndicatorView.class]){
_spinner = (UIActivityIndicatorView *)_originalView;
}
}
#pragma mark private method
//同一属性不同赋值方式转化
- (void)setFont:(float)font{
if (self.label) {
self.label.font = [UIFont systemFontOfSize:font];
}else if (self.textField) {
self.textField.font = [UIFont systemFontOfSize:font];
}else if (self.button){
self.button.titleLabel.font = [UIFont systemFontOfSize:font];
}else if (self.textView){
self.textView.font = [UIFont systemFontOfSize:font];
}
}
@end
2、UIView+XRChain
这个文件主要是对XRChainMaker文件的一个封装，其中涉及的代码简单，但也是整个工程的另一个核心，通过对UIView进行方法扩展，使其具备XRChainMaker的一切能力，也是开发者最终应用的文件，就像大家直接引用"Masnory.h"一样。
废话不多说，直接上代码：
UIView+XRChain.h
#import <UIKit/UIKit.h>
#import "XRChainMaker.h"
@interface UIView (XRChain)
@property (nonatomic) XRChainMaker *XRMake;
- (void)xr_makeChains:(void(^)(XRChainMaker *make))block;
- (XRChainMaker *)xr_make;
@end
UIView+XRChain.m
#import "UIView+XRChain.h"
#import <objc/runtime.h>
const char *keyOfMethod;
@implementation UIView (XRChain)
- (XRChainMaker *)XRMake{
return objc_getAssociatedObject(self, _cmd);
}
- (void)setXRMake:(XRChainMaker *)XRMake{
objc_setAssociatedObject(self, @selector(XRMake), XRMake, OBJC_ASSOCIATION_RETAIN);
}
- (void)xr_makeChains:(void(^)(XRChainMaker *make))block{
XRChainMaker *chainMaker = [[XRChainMaker alloc]init];
chainMaker.originalView = self;
block(chainMaker);
}
- (XRChainMaker *)xr_make{
XRChainMaker *chainMaker = [self XRMake];
if (!chainMaker) {
chainMaker = [[XRChainMaker alloc] init];
chainMaker.originalView = self;
}
return chainMaker;
}
@end
应用实例
先导入头文件
#import "UIView+XRChain.h"
拿UIButton举例：
- (void)viewDidLoad {
[super viewDidLoad];
self.view.backgroundColor = [UIColor cyanColor];
UIButton *btn = [UIButton buttonWithType:UIButtonTypeCustom];
btn.frame = CGRectMake(100, 100, 100, 100);
[btn xr_makeChains:^(XRChainMaker *make) {
make.title(@"点我",UIControlStateNormal)
.titleColor([UIColor whiteColor],UIControlStateNormal)
.bgColor([UIColor redColor])
.boldFont(14.f)
.tag(1)
.horizontalAlignment(UIControlContentHorizontalAlignmentCenter)
.addAction(self,@selector(buttonClick:),UIControlEventTouchUpInside)
// .hidden(YES)
.cornerRadius(5.f)
.addToSuperView(self.view);
}];
// Do any additional setup after loading the view, typically from a nib.
}
- (void)buttonClick:(UIButton *)sender{
NSLog(@"%s",__FUNCTION__);
}
效果图：
效果图
点击按钮输出：
XRChain[402:96091] -[ViewController buttonClick:]
