Object-C之代码艺术

代码的整体可读性：功能菜单

- (void)dealloc { /* ... */ }
- (instancetype)init { /* ... */ }

#pragma mark - View Lifecycle

- (void)viewDidLoad { /* ... */ }
- (void)viewWillAppear:(BOOL)animated { /* ... */ }
- (void)didReceiveMemoryWarning { /* ... */ }

#pragma mark - Custom Accessors

- (void)setCustomProperty:(id)value { /* ... */ }
- (id)customProperty { /* ... */ }

#pragma mark - IBActions

- (IBAction)submitData:(id)sender { /* ... */ }

#pragma mark - Public

- (void)publicMethod { /* ... */ }

#pragma mark - Private

- (void)zoc_privateMethod { /* ... */ }

#pragma mark - UITableViewDataSource

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath { /* ... */ }

#pragma mark - ZOCSuperclass

// ... overridden methods from ZOCSuperclass

#pragma mark - NSObject

- (NSString *)description { /* ... */ }

---

条件语句

---

有条件的机构应始终使用，即使有条件的机构可以不带括号（例如，它只是一条线），以防止错误写括号。这些错误包括增加第二条生产线，并期待它成为if语句的一部分。另一个更危险的缺陷，可能会出现在那里行“里面的”if语句已被注释掉，并在下一行不知不觉成为if语句的一部分。

should be

if (!error) {
    return success;
}

Not

if (!error)
    return success;

// or
if (!error) return success;

should be

- (void)someMethod {
  if (![someOther boolValue]) {
      return;
  }

  //Do something important
}

Not

- (void)someMethod {
  if ([someOther boolValue]) {
    //Do something important
  }
}

Yoda conditions

should be

if ([myValue isEqual:@42]) { ...

Not

if ([@42 isEqual:myValue]) { ...

nil and BOOL judge

should be

if (someObject) { ...
if (![someObject boolValue]) { ...
if (!someObject) { ...

Not

if (someObject == YES) { ... // Wrong
if (myRawValue == YES) { ... // Never do this.
if ([someObject boolValue] == NO) { ...

Case Statements

switch (menuType) { // 枚举
    case CC_EnumNone:
        // ...
        break;
    case CC_EnumValue1:
        // ...
        break;
    case CC_EnumValue2:
        // ...
        break;
}

Enumerated Types

typedef NS_ENUM(NSUInteger, CC_MachineState) {
    CC_MachineStateNone,
    CC_MachineStateIdle,
    CC_MachineStateRunning,
    CC_MachineStatePaused
};

---

命名

• Methods

should be

- (void)setExampleText:(NSString *)text image:(UIImage *)image;
- (void)sendAction:(SEL)aSelector to:(id)anObject forAllCells:(BOOL)flag;
- (id)viewWithTag:(NSInteger)tag;
- (instancetype)initWithWidth:(CGFloat)width height:(CGFloat)height;

Not

- (void)setT:(NSString *)text i:(UIImage *)image;
- (void)sendAction:(SEL)aSelector :(id)anObject :(BOOL)flag;
- (id)taggedView:(NSInteger)tag;
- (instancetype)initWithWidth:(CGFloat)width andHeight:(CGFloat)height;
- (instancetype)initWith:(int)width and:(int)height;  // Never do this.

• 代码解耦及加强可读性
  示例应用场景：假设有个Person类，需要喝水，根据职责划分，我们需要另外一个类Cup来完成喝水的动作，代码如下：

//Person.h
@interface Person:NSObject
- (void)drink;
@end

// Cup.h
@interface Cup:NSObject
- (id)provideWater;
@end

很明显Person和Cup间要完成喝水动作，一定会产生耦合，我们来看看OC中不同耦合方式下调用，代码的质量比较

方式一：.m引用

在.m文件导入Cup.h，同时生成临时的Cup对象来调用Cup中的方法。

#import "Person.h"
#import "Cup.h"

@implementation Person

- (void)drink {
    Cup *c = [Cup new];
    id water = [c provideWater];
    [self sip:water];
}

- (void)sip:(id)water 
{
  // sip water
}

@end

方式二: .h Property

避免方式一直接在.m中应用导致耦合不清晰，可以将耦合的部分声明放在.h中，提高代码可读性

// Person.h
@interface Person:NSObject
@property (nonatomic, strong) Cup *cup;
- (void)drink;

@end

// Person.m
@implementation Person
- (void)drink {
    self.cup = [Cup new];
    id water = [self.cup provideWater];
    [self sip:water];
}

- (void)sip:(id)water
{
  // sip water
}

@end