iOS开发性能最佳实践之——容易出现耗时阻塞的检查清单(持续更新)

剪贴板读取

dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
   UIPasteboard *pasteboard = [UIPasteboard generalPasteboard]; 
   if (pasteboard.string.length > 0) {//这个方法会阻塞线程
      NSString *text = [pasteboard.string copy];
      [pasteboard setValue:@"" forPasteboardType:UIPasteboardNameGeneral];
      if (text == nil || [text isEqualToString:@""]) {
          return ;
      }
      dispatch_async(dispatch_get_main_queue(), ^{
          [self processShareCode:text];
      });
   }
});

日期格式化

NSDateFormatter *formatter = [[NSDateFormatter alloc] init];
[formatter setDateStyle:NSDateFormatterShortStyle];
[formatter setDateFormat:@"yyyy#MM#dd#HH:mm#ss"];
NSString *result = [formatter stringFromDate:date];

文件读取

我们通常会使用NSFileManager来读取文件，但是NSFileManager读取文件并不是性能最好的,推荐使用stat.h里的’int stat(const char , struct stat ) __DARWIN_INODE64(stat);’方法。

NSFileManager

mach_timebase_info_data_t info;  
if (mach_timebase_info(&info) != KERN_SUCCESS) return -1.0; 
__darwin_off_t fileSize1 = 0;
uint64_t start = mach_absolute_time();
for (NSInteger i = 0; i <= 10000; i++) {
    NSDictionary<NSFileAttributeKey, id>* attributes = [[NSFileManager defaultManager] attributesOfItemAtPath:imagePath error:nil];
    fileSize1= [attributes fileSize];
}
uint64_t end = mach_absolute_time();
uint64_t elapsed = end - start;  
uint64_t nanos1 = elapsed * info.numer / info.denom;
return (CGFloat)nanos / NSEC_PER_SEC;

stat

mach_timebase_info_data_t info;  
 if (mach_timebase_info(&info) != KERN_SUCCESS) return -1.0; 
 __darwin_off_t fileSize = 0;
 uint64_t start = mach_absolute_time();
 for (NSInteger i = 0; i <= 10000; i++) {
     int rs = stat(filePath, &statBuf);
     fileSize= statBuf.st_size;
 }
 uint64_t end = mach_absolute_time();
 uint64_t elapsed = end - start;  
 uint64_t nanos1 = elapsed * info.numer / info.denom;
 return (CGFloat)nanos / NSEC_PER_SEC;