iOS开发规范&建议

NSURL *url = ({ NSString *urlString = [NSString stringWithFormat:@"%@/%@", baseURLString, endpoint];
[NSURL URLWithString:urlString];
});

#pragma clang diagnostic push
#pragma clang diagnostic ignored "-Warc-performSelector-leaks"
[myObj performSelector:mySelector withObject:name];
#pragma clang diagnostic pop

#pragma unused (foo)
明确定义错误和警告
#error Whoa, buddy, you need to check for zero here!
#warning Dude, don‘t compare floating point numbers like this!

__weak typeof(self) weakSelf = self;
dispatch_block_t block = ^{
[weakSelf doSomething]; // weakSelf != nil
// preemption, weakSelf turned nil
[weakSelf doSomethingElse]; // weakSelf == nil
};

__weak typeof(self) weakSelf = self;
myObj.myBlock = ^{
__strong typeof(self) strongSelf = weakSelf;
if (strongSelf) {
[strongSelf doSomething]; // strongSelf != nil
// preemption, strongSelf still not nil（抢占的时候，strongSelf 还是非 nil 的)
[strongSelf doSomethingElse]; // strongSelf != nil 
}
else { // Probably nothing... return;
}
};

// 不推荐写法
typedef enum{
UIControlStateNormal = 0,
UIControlStateHighlighted = 1 << 0,
UIControlStateDisabled = 1 << 1,
} UIControlState;

// 推荐写法
typedef NS_OPTIONS(NSUInteger, UIControlState) {
UIControlStateNormal = 0,
UIControlStateHighlighted = 1 << 0,
UIControlStateDisabled = 1 << 1,
};

// 推荐写法
[self.tableView registerNib:[UINib nibWithNibName:NSStringFromClass([DXRecommendTagVCell class]) bundle:nil] forCellReuseIdentifier:ID];

// 不推荐写法
[self.tableView registerNib:[UINib nibWithNibName:@"DXRecommendTagVCell" bundle:nil] forCellReuseIdentifier:ID];

// 注意:父类中的方法加`NS_REQUIRES_SUPER`,子类重写才有警告提示
- (void)prepare NS_REQUIRES_SUPER;

if (vc.isViewLoaded) return;

@property (nonatomic,strong) NSMutableArray *topicsM;

//建议
NSInteger arrayCount = [self.array count];
view.backgroundColor = [UIColor orangeColor];
[UIApplication sharedApplication].delegate;

//不建议
NSInteger arrayCount = self.array.count;
[view setBackgroundColor:[UIColor orangeColor]];
UIApplication.sharedApplication.delegate;

建议这样写
- (CGFloat)tableView:(UITableView *)tableView heightForRowAtIndexPath:(NSIndexPath *)indexPath
{
if (indexPath.row == 0) return 44;
if (indexPath.row == 1) return 80;
if (indexPath.row == 2) return 50;
return 44;
}

- (CGFloat)tableView:(UITableView *)tableView heightForRowAtIndexPath:(NSIndexPath *)indexPath
{
if (indexPath.row == 0) {
return 44;
}else if (indexPath.row == 1){
return 80;
}else if (indexPath.row == 2){
return 50;
}else{
return 44;
}
}

- (void)loadNewRecommendTags
{
return;

[SVProgressHUD show];
// 取消之前的任务
[self.manager.tasks makeObjectsPerformSelector:@selector(cancel)];
NSMutableDictionary *params = [NSMutableDictionary dictionary];

params[@"a"] = @"tag_recommend";
params[@"c"] = @"topic";
params[@"action"] = @"sub";
[self.manager GET:DXCommonUrlPath parameters:params success:^(NSURLSessionDataTask * _Nonnull task, id _Nonnull responseObject) {

self.recommendTag = [DXRecommendTag mj_objectArrayWithKeyValuesArray:responseObject];
[self.tableView reloadData];
[SVProgressHUD dismiss];
} failure:^(NSURLSessionDataTask * _Nullable task, NSError * _Nonnull error) {
DXLog(@"%@",error);
[SVProgressHUD dismiss];
}];
}

[UIApplication sharedApplication].keyWindow.rootViewController
代替
self.window.rootViewController,因为程序可能不止一个window,self.window可能不是主窗口;

用CGSizeZero 代替 CGSizeMake(0,0);
CGRectZero代替CGRectMake(0, 0, 0, 0);
CGPointZero代替CGPointMake(0, 0)

UIKIT_EXTERN NSString *const UIKeyboardWillChangeFrameNotification
而不是,下面代码;因为键盘可能因为改变输入法,切换成表情输入,切换成英文,那么frame可能会变高,变矮,不一定会发出下面这些通知,但是肯定会发上面的通知

UIKIT_EXTERN?NSString *const UIKeyboardWillShowNotification;
UIKIT_EXTERN?NSString *const UIKeyboardDidShowNotification;
UIKIT_EXTERN?NSString *const UIKeyboardWillHideNotification;
UIKIT_EXTERN?NSString *const UIKeyboardDidHideNotification;

NSString *const buttonDidClickNotification = @"buttonDidClickNotification";

CGFloat contentH = textW * self.height / self.width;

// 判断相册是否可以打开
if (![UIImagePickerController isSourceTypeAvailable:UIImagePickerControllerSourceTypePhotoLibrary]) return;

// 判断相机是否可以打开
if (![UIImagePickerController isSourceTypeAvailable:UIImagePickerControllerSourceTypeCamera]) return;

self.navigationItem.title = @“标题”
而不建议
self.title = @“标题”;

self.loginBtn.layer.cornerRadius = 5;
self.loginBtn.layer.masksToBounds = YES;

@property (nonatomic,strong) NSMutableArray *newTopicsM;
注意:如果newtopicsM是一个单词(区别于驼峰标志),这样写不会报错;如果是基本数据类型则不会报错,比如
@property (nonatomic,assign) int newNumber;

- (instancetype)initWithWidth:(CGFloat)width height:(CGFloat)height;
而不应该
- (instancetype)initWithWidth:(CGFloat)width andHeight:(CGFloat)height;